From 0f67f04ffcb592d065a20862a82d4539e0f8e909 Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Red Hat)" Date: Tue, 3 Feb 2015 11:56:20 -0500 Subject: tracing: Only create tracer options files if directory exists Do not bother creating tracer options if no tracing directory exists. If a tracer is enabled via the command line, and is started before the tracing directory is created, then it wont have its tracer specific options created. Signed-off-by: Steven Rostedt --- kernel/trace/trace.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) (limited to 'kernel/trace') diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 38c613ede10d..d4627f15407a 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -4172,8 +4172,11 @@ static int tracing_set_tracer(struct trace_array *tr, const char *buf) free_snapshot(tr); } #endif - /* Currently, only the top instance has options */ - if (tr->flags & TRACE_ARRAY_FL_GLOBAL) { + /* + * Only enable if the directory has been created already. + * Currently, only the top instance has options + */ + if (tr->dir && tr->flags & TRACE_ARRAY_FL_GLOBAL) { destroy_trace_option_files(topts); topts = create_trace_option_files(tr, t); } -- cgit v1.2.3-59-g8ed1b From 09d23a1d8a82e814bd56a4f121b80ea8214ac49d Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Red Hat)" Date: Tue, 3 Feb 2015 12:45:53 -0500 Subject: tracing: Create cmdline tracer options on tracing fs init The options for cmdline tracers are not created if the debugfs system is not ready yet. If tracing has started before debugfs is up, then the option files for the tracer are not created. Create them when creating the tracing directory if the current tracer requires option files. Signed-off-by: Steven Rostedt --- kernel/trace/trace.c | 30 +++++++++++++++++++++--------- 1 file changed, 21 insertions(+), 9 deletions(-) (limited to 'kernel/trace') diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index d4627f15407a..05e0e50539fc 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -4105,9 +4105,24 @@ static void tracing_set_nop(struct trace_array *tr) tr->current_trace = &nop_trace; } -static int tracing_set_tracer(struct trace_array *tr, const char *buf) +static void update_tracer_options(struct trace_array *tr, struct tracer *t) { static struct trace_option_dentry *topts; + + /* Only enable if the directory has been created already. */ + if (!tr->dir) + return; + + /* Currently, only the top instance has options */ + if (!(tr->flags & TRACE_ARRAY_FL_GLOBAL)) + return; + + destroy_trace_option_files(topts); + topts = create_trace_option_files(tr, t); +} + +static int tracing_set_tracer(struct trace_array *tr, const char *buf) +{ struct tracer *t; #ifdef CONFIG_TRACER_MAX_TRACE bool had_max_tr; @@ -4172,14 +4187,7 @@ static int tracing_set_tracer(struct trace_array *tr, const char *buf) free_snapshot(tr); } #endif - /* - * Only enable if the directory has been created already. - * Currently, only the top instance has options - */ - if (tr->dir && tr->flags & TRACE_ARRAY_FL_GLOBAL) { - destroy_trace_option_files(topts); - topts = create_trace_option_files(tr, t); - } + update_tracer_options(tr, t); #ifdef CONFIG_TRACER_MAX_TRACE if (t->use_max_tr && !had_max_tr) { @@ -6578,6 +6586,10 @@ static __init int tracer_init_debugfs(void) create_trace_options_dir(&global_trace); + /* If the tracer was started via cmdline, create options for it here */ + if (global_trace.current_trace != &nop_trace) + update_tracer_options(&global_trace, global_trace.current_trace); + return 0; } -- cgit v1.2.3-59-g8ed1b From 8434dc9340cd2e117fc944cf7526263bf490a52a Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Red Hat)" Date: Tue, 20 Jan 2015 12:13:40 -0500 Subject: tracing: Convert the tracing facility over to use tracefs debugfs was fine for the tracing facility as a quick way to get an interface. Now that tracing has matured, it should separate itself from debugfs such that it can be mounted separately without needing to mount all of debugfs with it. That is, users resist using tracing because it requires mounting debugfs. Having tracing have its own file system lets users get the features of tracing without needing to bring in the rest of the kernel's debug infrastructure. Another reason for tracefs is that debubfs does not support mkdir. Currently, to create instances, one does a mkdir in the tracing/instance directory. This is implemented via a hack that forces debugfs to do something it is not intended on doing. By converting over to tracefs, this hack can be removed and mkdir can be properly implemented. This patch does not address this yet, but it lays the ground work for that to be done. Signed-off-by: Steven Rostedt --- kernel/trace/ftrace.c | 22 +++++++-------- kernel/trace/trace.c | 55 +++++++++++++++++++++--------------- kernel/trace/trace.h | 2 +- kernel/trace/trace_events.c | 32 ++++++++++----------- kernel/trace/trace_functions_graph.c | 7 ++--- kernel/trace/trace_kprobe.c | 10 +++---- kernel/trace/trace_probe.h | 2 +- kernel/trace/trace_stat.c | 10 +++---- 8 files changed, 74 insertions(+), 66 deletions(-) (limited to 'kernel/trace') diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 45e5cb143d17..fcc0e7052a79 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -18,7 +18,7 @@ #include #include #include -#include +#include #include #include #include @@ -1008,7 +1008,7 @@ static struct tracer_stat function_stats __initdata = { .stat_show = function_stat_show }; -static __init void ftrace_profile_debugfs(struct dentry *d_tracer) +static __init void ftrace_profile_tracefs(struct dentry *d_tracer) { struct ftrace_profile_stat *stat; struct dentry *entry; @@ -1044,15 +1044,15 @@ static __init void ftrace_profile_debugfs(struct dentry *d_tracer) } } - entry = debugfs_create_file("function_profile_enabled", 0644, + entry = tracefs_create_file("function_profile_enabled", 0644, d_tracer, NULL, &ftrace_profile_fops); if (!entry) - pr_warning("Could not create debugfs " + pr_warning("Could not create tracefs " "'function_profile_enabled' entry\n"); } #else /* CONFIG_FUNCTION_PROFILER */ -static __init void ftrace_profile_debugfs(struct dentry *d_tracer) +static __init void ftrace_profile_tracefs(struct dentry *d_tracer) { } #endif /* CONFIG_FUNCTION_PROFILER */ @@ -4690,7 +4690,7 @@ void ftrace_destroy_filter_files(struct ftrace_ops *ops) mutex_unlock(&ftrace_lock); } -static __init int ftrace_init_dyn_debugfs(struct dentry *d_tracer) +static __init int ftrace_init_dyn_tracefs(struct dentry *d_tracer) { trace_create_file("available_filter_functions", 0444, @@ -4998,7 +4998,7 @@ static int __init ftrace_nodyn_init(void) } core_initcall(ftrace_nodyn_init); -static inline int ftrace_init_dyn_debugfs(struct dentry *d_tracer) { return 0; } +static inline int ftrace_init_dyn_tracefs(struct dentry *d_tracer) { return 0; } static inline void ftrace_startup_enable(int command) { } static inline void ftrace_startup_all(int command) { } /* Keep as macros so we do not need to define the commands */ @@ -5451,7 +5451,7 @@ static const struct file_operations ftrace_pid_fops = { .release = ftrace_pid_release, }; -static __init int ftrace_init_debugfs(void) +static __init int ftrace_init_tracefs(void) { struct dentry *d_tracer; @@ -5459,16 +5459,16 @@ static __init int ftrace_init_debugfs(void) if (IS_ERR(d_tracer)) return 0; - ftrace_init_dyn_debugfs(d_tracer); + ftrace_init_dyn_tracefs(d_tracer); trace_create_file("set_ftrace_pid", 0644, d_tracer, NULL, &ftrace_pid_fops); - ftrace_profile_debugfs(d_tracer); + ftrace_profile_tracefs(d_tracer); return 0; } -fs_initcall(ftrace_init_debugfs); +fs_initcall(ftrace_init_tracefs); /** * ftrace_kill - kill ftrace diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 05e0e50539fc..6c4739bee4bb 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -20,6 +20,7 @@ #include #include #include +#include #include #include #include @@ -5828,6 +5829,14 @@ static inline __init int register_snapshot_cmd(void) { return 0; } static struct dentry *tracing_get_dentry(struct trace_array *tr) { + if (WARN_ON(!tr->dir)) + return ERR_PTR(-ENODEV); + + /* Top directory uses NULL as the parent */ + if (tr->flags & TRACE_ARRAY_FL_GLOBAL) + return NULL; + + /* All sub buffers have a descriptor */ return tr->dir; } @@ -5842,10 +5851,10 @@ static struct dentry *tracing_dentry_percpu(struct trace_array *tr, int cpu) if (IS_ERR(d_tracer)) return NULL; - tr->percpu_dir = debugfs_create_dir("per_cpu", d_tracer); + tr->percpu_dir = tracefs_create_dir("per_cpu", d_tracer); WARN_ONCE(!tr->percpu_dir, - "Could not create debugfs directory 'per_cpu/%d'\n", cpu); + "Could not create tracefs directory 'per_cpu/%d'\n", cpu); return tr->percpu_dir; } @@ -5862,7 +5871,7 @@ trace_create_cpu_file(const char *name, umode_t mode, struct dentry *parent, } static void -tracing_init_debugfs_percpu(struct trace_array *tr, long cpu) +tracing_init_tracefs_percpu(struct trace_array *tr, long cpu) { struct dentry *d_percpu = tracing_dentry_percpu(tr, cpu); struct dentry *d_cpu; @@ -5872,9 +5881,9 @@ tracing_init_debugfs_percpu(struct trace_array *tr, long cpu) return; snprintf(cpu_dir, 30, "cpu%ld", cpu); - d_cpu = debugfs_create_dir(cpu_dir, d_percpu); + d_cpu = tracefs_create_dir(cpu_dir, d_percpu); if (!d_cpu) { - pr_warning("Could not create debugfs '%s' entry\n", cpu_dir); + pr_warning("Could not create tracefs '%s' entry\n", cpu_dir); return; } @@ -6026,9 +6035,9 @@ struct dentry *trace_create_file(const char *name, { struct dentry *ret; - ret = debugfs_create_file(name, mode, parent, data, fops); + ret = tracefs_create_file(name, mode, parent, data, fops); if (!ret) - pr_warning("Could not create debugfs '%s' entry\n", name); + pr_warning("Could not create tracefs '%s' entry\n", name); return ret; } @@ -6045,9 +6054,9 @@ static struct dentry *trace_options_init_dentry(struct trace_array *tr) if (IS_ERR(d_tracer)) return NULL; - tr->options = debugfs_create_dir("options", d_tracer); + tr->options = tracefs_create_dir("options", d_tracer); if (!tr->options) { - pr_warning("Could not create debugfs directory 'options'\n"); + pr_warning("Could not create tracefs directory 'options'\n"); return NULL; } @@ -6116,7 +6125,7 @@ destroy_trace_option_files(struct trace_option_dentry *topts) return; for (cnt = 0; topts[cnt].opt; cnt++) - debugfs_remove(topts[cnt].entry); + tracefs_remove(topts[cnt].entry); kfree(topts); } @@ -6205,7 +6214,7 @@ static const struct file_operations rb_simple_fops = { struct dentry *trace_instance_dir; static void -init_tracer_debugfs(struct trace_array *tr, struct dentry *d_tracer); +init_tracer_tracefs(struct trace_array *tr, struct dentry *d_tracer); static int allocate_trace_buffer(struct trace_array *tr, struct trace_buffer *buf, int size) @@ -6321,17 +6330,17 @@ static int new_instance_create(const char *name) if (allocate_trace_buffers(tr, trace_buf_size) < 0) goto out_free_tr; - tr->dir = debugfs_create_dir(name, trace_instance_dir); + tr->dir = tracefs_create_dir(name, trace_instance_dir); if (!tr->dir) goto out_free_tr; ret = event_trace_add_tracer(tr->dir, tr); if (ret) { - debugfs_remove_recursive(tr->dir); + tracefs_remove_recursive(tr->dir); goto out_free_tr; } - init_tracer_debugfs(tr, tr->dir); + init_tracer_tracefs(tr, tr->dir); list_add(&tr->list, &ftrace_trace_arrays); @@ -6404,7 +6413,7 @@ static int instance_mkdir (struct inode *inode, struct dentry *dentry, umode_t m return -ENOENT; /* - * The inode mutex is locked, but debugfs_create_dir() will also + * The inode mutex is locked, but tracefs_create_dir() will also * take the mutex. As the instances directory can not be destroyed * or changed in any other way, it is safe to unlock it, and * let the dentry try. If two users try to make the same dir at @@ -6434,7 +6443,7 @@ static int instance_rmdir(struct inode *inode, struct dentry *dentry) mutex_unlock(&dentry->d_inode->i_mutex); /* - * The inode mutex is locked, but debugfs_create_dir() will also + * The inode mutex is locked, but tracefs_create_dir() will also * take the mutex. As the instances directory can not be destroyed * or changed in any other way, it is safe to unlock it, and * let the dentry try. If two users try to make the same dir at @@ -6459,7 +6468,7 @@ static const struct inode_operations instance_dir_inode_operations = { static __init void create_trace_instances(struct dentry *d_tracer) { - trace_instance_dir = debugfs_create_dir("instances", d_tracer); + trace_instance_dir = tracefs_create_dir("instances", d_tracer); if (WARN_ON(!trace_instance_dir)) return; @@ -6468,7 +6477,7 @@ static __init void create_trace_instances(struct dentry *d_tracer) } static void -init_tracer_debugfs(struct trace_array *tr, struct dentry *d_tracer) +init_tracer_tracefs(struct trace_array *tr, struct dentry *d_tracer) { int cpu; @@ -6522,7 +6531,7 @@ init_tracer_debugfs(struct trace_array *tr, struct dentry *d_tracer) #endif for_each_tracing_cpu(cpu) - tracing_init_debugfs_percpu(tr, cpu); + tracing_init_tracefs_percpu(tr, cpu); } @@ -6550,10 +6559,10 @@ struct dentry *tracing_init_dentry(void) return ERR_PTR(-ENOMEM); } - return tr->dir; + return NULL; } -static __init int tracer_init_debugfs(void) +static __init int tracer_init_tracefs(void) { struct dentry *d_tracer; @@ -6563,7 +6572,7 @@ static __init int tracer_init_debugfs(void) if (IS_ERR(d_tracer)) return 0; - init_tracer_debugfs(&global_trace, d_tracer); + init_tracer_tracefs(&global_trace, d_tracer); trace_create_file("tracing_thresh", 0644, d_tracer, &global_trace, &tracing_thresh_fops); @@ -6925,5 +6934,5 @@ __init static int clear_boot_tracer(void) return 0; } -fs_initcall(tracer_init_debugfs); +fs_initcall(tracer_init_tracefs); late_initcall(clear_boot_tracer); diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h index dd8205a35760..d951deddec89 100644 --- a/kernel/trace/trace.h +++ b/kernel/trace/trace.h @@ -334,7 +334,7 @@ struct tracer_flags { /** - * struct tracer - a specific tracer and its callbacks to interact with debugfs + * struct tracer - a specific tracer and its callbacks to interact with tracefs * @name: the name chosen to select it on the available_tracers file * @init: called when one switches to this tracer (echo name > current_tracer) * @reset: called when one switches to another tracer diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c index db54dda10ccc..0d2e47370ee7 100644 --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -13,7 +13,7 @@ #include #include #include -#include +#include #include #include #include @@ -480,7 +480,7 @@ static void remove_subsystem(struct ftrace_subsystem_dir *dir) return; if (!--dir->nr_events) { - debugfs_remove_recursive(dir->entry); + tracefs_remove_recursive(dir->entry); list_del(&dir->list); __put_system_dir(dir); } @@ -499,7 +499,7 @@ static void remove_event_file_dir(struct ftrace_event_file *file) } spin_unlock(&dir->d_lock); - debugfs_remove_recursive(dir); + tracefs_remove_recursive(dir); } list_del(&file->list); @@ -1526,7 +1526,7 @@ event_subsystem_dir(struct trace_array *tr, const char *name, } else __get_system(system); - dir->entry = debugfs_create_dir(name, parent); + dir->entry = tracefs_create_dir(name, parent); if (!dir->entry) { pr_warn("Failed to create system directory %s\n", name); __put_system(system); @@ -1539,12 +1539,12 @@ event_subsystem_dir(struct trace_array *tr, const char *name, dir->subsystem = system; file->system = dir; - entry = debugfs_create_file("filter", 0644, dir->entry, dir, + entry = tracefs_create_file("filter", 0644, dir->entry, dir, &ftrace_subsystem_filter_fops); if (!entry) { kfree(system->filter); system->filter = NULL; - pr_warn("Could not create debugfs '%s/filter' entry\n", name); + pr_warn("Could not create tracefs '%s/filter' entry\n", name); } trace_create_file("enable", 0644, dir->entry, dir, @@ -1585,9 +1585,9 @@ event_create_dir(struct dentry *parent, struct ftrace_event_file *file) d_events = parent; name = ftrace_event_name(call); - file->dir = debugfs_create_dir(name, d_events); + file->dir = tracefs_create_dir(name, d_events); if (!file->dir) { - pr_warn("Could not create debugfs '%s' directory\n", name); + pr_warn("Could not create tracefs '%s' directory\n", name); return -1; } @@ -2228,7 +2228,7 @@ static inline int register_event_cmds(void) { return 0; } /* * The top level array has already had its ftrace_event_file * descriptors created in order to allow for early events to - * be recorded. This function is called after the debugfs has been + * be recorded. This function is called after the tracefs has been * initialized, and we now have to create the files associated * to the events. */ @@ -2311,16 +2311,16 @@ create_event_toplevel_files(struct dentry *parent, struct trace_array *tr) struct dentry *d_events; struct dentry *entry; - entry = debugfs_create_file("set_event", 0644, parent, + entry = tracefs_create_file("set_event", 0644, parent, tr, &ftrace_set_event_fops); if (!entry) { - pr_warn("Could not create debugfs 'set_event' entry\n"); + pr_warn("Could not create tracefs 'set_event' entry\n"); return -ENOMEM; } - d_events = debugfs_create_dir("events", parent); + d_events = tracefs_create_dir("events", parent); if (!d_events) { - pr_warn("Could not create debugfs 'events' directory\n"); + pr_warn("Could not create tracefs 'events' directory\n"); return -ENOMEM; } @@ -2412,7 +2412,7 @@ int event_trace_del_tracer(struct trace_array *tr) down_write(&trace_event_sem); __trace_remove_event_dirs(tr); - debugfs_remove_recursive(tr->event_dir); + tracefs_remove_recursive(tr->event_dir); up_write(&trace_event_sem); tr->event_dir = NULL; @@ -2534,10 +2534,10 @@ static __init int event_trace_init(void) if (IS_ERR(d_tracer)) return 0; - entry = debugfs_create_file("available_events", 0444, d_tracer, + entry = tracefs_create_file("available_events", 0444, d_tracer, tr, &ftrace_avail_fops); if (!entry) - pr_warn("Could not create debugfs 'available_events' entry\n"); + pr_warn("Could not create tracefs 'available_events' entry\n"); if (trace_define_common_fields()) pr_warn("tracing: Failed to allocate common fields"); diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c index 2d25ad1526bb..9cfea4c6d314 100644 --- a/kernel/trace/trace_functions_graph.c +++ b/kernel/trace/trace_functions_graph.c @@ -6,7 +6,6 @@ * is Copyright (c) Steven Rostedt * */ -#include #include #include #include @@ -151,7 +150,7 @@ ftrace_push_return_trace(unsigned long ret, unsigned long func, int *depth, * The curr_ret_stack is initialized to -1 and get increased * in this function. So it can be less than -1 only if it was * filtered out via ftrace_graph_notrace_addr() which can be - * set from set_graph_notrace file in debugfs by user. + * set from set_graph_notrace file in tracefs by user. */ if (current->curr_ret_stack < -1) return -EBUSY; @@ -1432,7 +1431,7 @@ static const struct file_operations graph_depth_fops = { .llseek = generic_file_llseek, }; -static __init int init_graph_debugfs(void) +static __init int init_graph_tracefs(void) { struct dentry *d_tracer; @@ -1445,7 +1444,7 @@ static __init int init_graph_debugfs(void) return 0; } -fs_initcall(init_graph_debugfs); +fs_initcall(init_graph_tracefs); static __init int init_graph_trace(void) { diff --git a/kernel/trace/trace_kprobe.c b/kernel/trace/trace_kprobe.c index b4a00def88f5..c1c6655847c8 100644 --- a/kernel/trace/trace_kprobe.c +++ b/kernel/trace/trace_kprobe.c @@ -1310,7 +1310,7 @@ static int unregister_kprobe_event(struct trace_kprobe *tk) return ret; } -/* Make a debugfs interface for controlling probe points */ +/* Make a tracefs interface for controlling probe points */ static __init int init_kprobe_trace(void) { struct dentry *d_tracer; @@ -1323,20 +1323,20 @@ static __init int init_kprobe_trace(void) if (IS_ERR(d_tracer)) return 0; - entry = debugfs_create_file("kprobe_events", 0644, d_tracer, + entry = tracefs_create_file("kprobe_events", 0644, d_tracer, NULL, &kprobe_events_ops); /* Event list interface */ if (!entry) - pr_warning("Could not create debugfs " + pr_warning("Could not create tracefs " "'kprobe_events' entry\n"); /* Profile interface */ - entry = debugfs_create_file("kprobe_profile", 0444, d_tracer, + entry = tracefs_create_file("kprobe_profile", 0444, d_tracer, NULL, &kprobe_profile_ops); if (!entry) - pr_warning("Could not create debugfs " + pr_warning("Could not create tracefs " "'kprobe_profile' entry\n"); return 0; } diff --git a/kernel/trace/trace_probe.h b/kernel/trace/trace_probe.h index 4f815fbce16d..19aff635841a 100644 --- a/kernel/trace/trace_probe.h +++ b/kernel/trace/trace_probe.h @@ -25,7 +25,7 @@ #include #include #include -#include +#include #include #include #include diff --git a/kernel/trace/trace_stat.c b/kernel/trace/trace_stat.c index 75e19e86c954..6cf935316769 100644 --- a/kernel/trace/trace_stat.c +++ b/kernel/trace/trace_stat.c @@ -12,7 +12,7 @@ #include #include #include -#include +#include #include "trace_stat.h" #include "trace.h" @@ -65,7 +65,7 @@ static void reset_stat_session(struct stat_session *session) static void destroy_session(struct stat_session *session) { - debugfs_remove(session->file); + tracefs_remove(session->file); __reset_stat_session(session); mutex_destroy(&session->stat_mutex); kfree(session); @@ -279,9 +279,9 @@ static int tracing_stat_init(void) if (IS_ERR(d_tracing)) return 0; - stat_dir = debugfs_create_dir("trace_stat", d_tracing); + stat_dir = tracefs_create_dir("trace_stat", d_tracing); if (!stat_dir) - pr_warning("Could not create debugfs " + pr_warning("Could not create tracefs " "'trace_stat' entry\n"); return 0; } @@ -291,7 +291,7 @@ static int init_stat_file(struct stat_session *session) if (!stat_dir && tracing_stat_init()) return -ENODEV; - session->file = debugfs_create_file(session->ts->name, 0644, + session->file = tracefs_create_file(session->ts->name, 0644, stat_dir, session, &tracing_stat_fops); if (!session->file) -- cgit v1.2.3-59-g8ed1b From f76180bc07abc399977bfbe8c43bf58c4570e893 Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Red Hat)" Date: Tue, 20 Jan 2015 15:48:46 -0500 Subject: tracing: Automatically mount tracefs on debugfs/tracing As tools currently rely on the tracing directory in debugfs, we can not just created a tracefs infrastructure and expect sysadmins to mount the new tracefs to have their old tools work. Instead, the debugfs tracing directory is still created and the tracefs file system is mounted there when the debugfs filesystem is mounted. No longer does the tracing infrastructure update the debugfs file system, but instead interacts with the tracefs file system. But now, it still appears to the user like nothing changed, except you also have the feature of mounting just the tracing system without needing all of debugfs! Cc: Al Viro Signed-off-by: Steven Rostedt --- kernel/trace/trace.c | 36 +++++++++++++++++++++++++++++++++--- 1 file changed, 33 insertions(+), 3 deletions(-) (limited to 'kernel/trace') diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 6c4739bee4bb..b4aa936509d2 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -32,6 +32,7 @@ #include #include #include +#include #include #include #include @@ -6535,6 +6536,28 @@ init_tracer_tracefs(struct trace_array *tr, struct dentry *d_tracer) } +static struct vfsmount *trace_automount(void *ingore) +{ + struct vfsmount *mnt; + struct file_system_type *type; + + /* + * To maintain backward compatibility for tools that mount + * debugfs to get to the tracing facility, tracefs is automatically + * mounted to the debugfs/tracing directory. + */ + type = get_fs_type("tracefs"); + if (!type) + return NULL; + mnt = vfs_kern_mount(type, 0, "tracefs", NULL); + put_filesystem(type); + if (IS_ERR(mnt)) + return NULL; + mntget(mnt); + + return mnt; +} + /** * tracing_init_dentry - initialize top level trace array * @@ -6546,14 +6569,21 @@ struct dentry *tracing_init_dentry(void) { struct trace_array *tr = &global_trace; + /* The top level trace array uses NULL as parent */ if (tr->dir) - return tr->dir; + return NULL; if (WARN_ON(!debugfs_initialized())) return ERR_PTR(-ENODEV); - tr->dir = debugfs_create_dir("tracing", NULL); - + /* + * As there may still be users that expect the tracing + * files to exist in debugfs/tracing, we must automount + * the tracefs file system there, so older tools still + * work with the newer kerenl. + */ + tr->dir = debugfs_create_automount("tracing", NULL, + trace_automount, NULL); if (!tr->dir) { pr_warn_once("Could not create debugfs directory 'tracing'\n"); return ERR_PTR(-ENOMEM); -- cgit v1.2.3-59-g8ed1b From eae473581cf93dad94ca833aa961c033c6a43924 Mon Sep 17 00:00:00 2001 From: "Steven Rostedt (Red Hat)" Date: Wed, 21 Jan 2015 10:01:39 -0500 Subject: tracing: Have mkdir and rmdir be part of tracefs The tracing "instances" directory can create sub tracing buffers with mkdir, and remove them with rmdir. As a mkdir will also create all the files and directories that control the sub buffer the inode mutexes need to be released before this is done, to avoid deadlocks. It is better to let the tracing system unlock the inode mutexes before calling the functions that create the files within the new directory (or deletes the files from the one being destroyed). Now that tracing has been converted over to tracefs, the tracefs file system can be modified to accommodate this feature. It still releases the locks, but the filesystem itself can take care of the ugly business and let the user just do what it needs. The tracing system now attaches a descriptor to the directory dentry that can have userspace create or remove sub directories. If this descriptor does not exist for a dentry, then that dentry can not be used to create other directories. This descriptor holds a mkdir and rmdir method that only takes a character string as an argument. The tracefs file system will first make a copy of the dentry name before releasing the locks. Then it will pass the copied name to the methods. It is up to the tracing system that supplied the methods to handle races with duplicate names and such as all the inode mutexes would be released when the functions are called. Cc: Al Viro Signed-off-by: Steven Rostedt --- fs/tracefs/inode.c | 151 +++++++++++++++++++++++++++++++++++++++++++----- include/linux/tracefs.h | 4 ++ kernel/trace/trace.c | 75 ++---------------------- 3 files changed, 145 insertions(+), 85 deletions(-) (limited to 'kernel/trace') diff --git a/fs/tracefs/inode.c b/fs/tracefs/inode.c index 0b9cf5cf24c9..d92bdf3b079a 100644 --- a/fs/tracefs/inode.c +++ b/fs/tracefs/inode.c @@ -50,6 +50,84 @@ static const struct file_operations tracefs_file_operations = { .llseek = noop_llseek, }; +static struct tracefs_dir_ops { + int (*mkdir)(const char *name); + int (*rmdir)(const char *name); +} tracefs_ops; + +static char *get_dname(struct dentry *dentry) +{ + const char *dname; + char *name; + int len = dentry->d_name.len; + + dname = dentry->d_name.name; + name = kmalloc(len + 1, GFP_KERNEL); + if (!name) + return NULL; + memcpy(name, dname, len); + name[len] = 0; + return name; +} + +static int tracefs_syscall_mkdir(struct inode *inode, struct dentry *dentry, umode_t mode) +{ + char *name; + int ret; + + name = get_dname(dentry); + if (!name) + return -ENOMEM; + + /* + * The mkdir call can call the generic functions that create + * the files within the tracefs system. It is up to the individual + * mkdir routine to handle races. + */ + mutex_unlock(&inode->i_mutex); + ret = tracefs_ops.mkdir(name); + mutex_lock(&inode->i_mutex); + + kfree(name); + + return ret; +} + +static int tracefs_syscall_rmdir(struct inode *inode, struct dentry *dentry) +{ + char *name; + int ret; + + name = get_dname(dentry); + if (!name) + return -ENOMEM; + + /* + * The rmdir call can call the generic functions that create + * the files within the tracefs system. It is up to the individual + * rmdir routine to handle races. + * This time we need to unlock not only the parent (inode) but + * also the directory that is being deleted. + */ + mutex_unlock(&inode->i_mutex); + mutex_unlock(&dentry->d_inode->i_mutex); + + ret = tracefs_ops.rmdir(name); + + mutex_lock_nested(&inode->i_mutex, I_MUTEX_PARENT); + mutex_lock(&dentry->d_inode->i_mutex); + + kfree(name); + + return ret; +} + +static const struct inode_operations tracefs_dir_inode_operations = { + .lookup = simple_lookup, + .mkdir = tracefs_syscall_mkdir, + .rmdir = tracefs_syscall_rmdir, +}; + static struct inode *tracefs_get_inode(struct super_block *sb) { struct inode *inode = new_inode(sb); @@ -334,6 +412,31 @@ struct dentry *tracefs_create_file(const char *name, umode_t mode, return end_creating(dentry); } +static struct dentry *__create_dir(const char *name, struct dentry *parent, + const struct inode_operations *ops) +{ + struct dentry *dentry = start_creating(name, parent); + struct inode *inode; + + if (IS_ERR(dentry)) + return NULL; + + inode = tracefs_get_inode(dentry->d_sb); + if (unlikely(!inode)) + return failed_creating(dentry); + + inode->i_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO; + inode->i_op = ops; + inode->i_fop = &simple_dir_operations; + + /* directory inodes start off with i_nlink == 2 (for "." entry) */ + inc_nlink(inode); + d_instantiate(dentry, inode); + inc_nlink(dentry->d_parent->d_inode); + fsnotify_mkdir(dentry->d_parent->d_inode, dentry); + return end_creating(dentry); +} + /** * tracefs_create_dir - create a directory in the tracefs filesystem * @name: a pointer to a string containing the name of the directory to @@ -353,26 +456,44 @@ struct dentry *tracefs_create_file(const char *name, umode_t mode, */ struct dentry *tracefs_create_dir(const char *name, struct dentry *parent) { - struct dentry *dentry = start_creating(name, parent); - struct inode *inode; + return __create_dir(name, parent, &simple_dir_inode_operations); +} - if (IS_ERR(dentry)) +/** + * tracefs_create_instance_dir - create the tracing instances directory + * @name: The name of the instances directory to create + * @parent: The parent directory that the instances directory will exist + * @mkdir: The function to call when a mkdir is performed. + * @rmdir: The function to call when a rmdir is performed. + * + * Only one instances directory is allowed. + * + * The instances directory is special as it allows for mkdir and rmdir to + * to be done by userspace. When a mkdir or rmdir is performed, the inode + * locks are released and the methhods passed in (@mkdir and @rmdir) are + * called without locks and with the name of the directory being created + * within the instances directory. + * + * Returns the dentry of the instances directory. + */ +struct dentry *tracefs_create_instance_dir(const char *name, struct dentry *parent, + int (*mkdir)(const char *name), + int (*rmdir)(const char *name)) +{ + struct dentry *dentry; + + /* Only allow one instance of the instances directory. */ + if (WARN_ON(tracefs_ops.mkdir || tracefs_ops.rmdir)) return NULL; - inode = tracefs_get_inode(dentry->d_sb); - if (unlikely(!inode)) - return failed_creating(dentry); + dentry = __create_dir(name, parent, &tracefs_dir_inode_operations); + if (!dentry) + return NULL; - inode->i_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO; - inode->i_op = &simple_dir_inode_operations; - inode->i_fop = &simple_dir_operations; + tracefs_ops.mkdir = mkdir; + tracefs_ops.rmdir = rmdir; - /* directory inodes start off with i_nlink == 2 (for "." entry) */ - inc_nlink(inode); - d_instantiate(dentry, inode); - inc_nlink(dentry->d_parent->d_inode); - fsnotify_mkdir(dentry->d_parent->d_inode, dentry); - return end_creating(dentry); + return dentry; } static inline int tracefs_positive(struct dentry *dentry) diff --git a/include/linux/tracefs.h b/include/linux/tracefs.h index 23e04ce21749..5b727a17beee 100644 --- a/include/linux/tracefs.h +++ b/include/linux/tracefs.h @@ -34,6 +34,10 @@ struct dentry *tracefs_create_dir(const char *name, struct dentry *parent); void tracefs_remove(struct dentry *dentry); void tracefs_remove_recursive(struct dentry *dentry); +struct dentry *tracefs_create_instance_dir(const char *name, struct dentry *parent, + int (*mkdir)(const char *name), + int (*rmdir)(const char *name)); + bool tracefs_initialized(void); #endif /* CONFIG_TRACING */ diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index b4aa936509d2..3c8913bac204 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -6292,7 +6292,7 @@ static void free_trace_buffers(struct trace_array *tr) #endif } -static int new_instance_create(const char *name) +static int instance_mkdir(const char *name) { struct trace_array *tr; int ret; @@ -6362,7 +6362,7 @@ static int new_instance_create(const char *name) } -static int instance_delete(const char *name) +static int instance_rmdir(const char *name) { struct trace_array *tr; int found = 0; @@ -6403,78 +6403,13 @@ static int instance_delete(const char *name) return ret; } -static int instance_mkdir (struct inode *inode, struct dentry *dentry, umode_t mode) -{ - struct dentry *parent; - int ret; - - /* Paranoid: Make sure the parent is the "instances" directory */ - parent = hlist_entry(inode->i_dentry.first, struct dentry, d_u.d_alias); - if (WARN_ON_ONCE(parent != trace_instance_dir)) - return -ENOENT; - - /* - * The inode mutex is locked, but tracefs_create_dir() will also - * take the mutex. As the instances directory can not be destroyed - * or changed in any other way, it is safe to unlock it, and - * let the dentry try. If two users try to make the same dir at - * the same time, then the new_instance_create() will determine the - * winner. - */ - mutex_unlock(&inode->i_mutex); - - ret = new_instance_create(dentry->d_iname); - - mutex_lock(&inode->i_mutex); - - return ret; -} - -static int instance_rmdir(struct inode *inode, struct dentry *dentry) -{ - struct dentry *parent; - int ret; - - /* Paranoid: Make sure the parent is the "instances" directory */ - parent = hlist_entry(inode->i_dentry.first, struct dentry, d_u.d_alias); - if (WARN_ON_ONCE(parent != trace_instance_dir)) - return -ENOENT; - - /* The caller did a dget() on dentry */ - mutex_unlock(&dentry->d_inode->i_mutex); - - /* - * The inode mutex is locked, but tracefs_create_dir() will also - * take the mutex. As the instances directory can not be destroyed - * or changed in any other way, it is safe to unlock it, and - * let the dentry try. If two users try to make the same dir at - * the same time, then the instance_delete() will determine the - * winner. - */ - mutex_unlock(&inode->i_mutex); - - ret = instance_delete(dentry->d_iname); - - mutex_lock_nested(&inode->i_mutex, I_MUTEX_PARENT); - mutex_lock(&dentry->d_inode->i_mutex); - - return ret; -} - -static const struct inode_operations instance_dir_inode_operations = { - .lookup = simple_lookup, - .mkdir = instance_mkdir, - .rmdir = instance_rmdir, -}; - static __init void create_trace_instances(struct dentry *d_tracer) { - trace_instance_dir = tracefs_create_dir("instances", d_tracer); + trace_instance_dir = tracefs_create_instance_dir("instances", d_tracer, + instance_mkdir, + instance_rmdir); if (WARN_ON(!trace_instance_dir)) return; - - /* Hijack the dir inode operations, to allow mkdir */ - trace_instance_dir->d_inode->i_op = &instance_dir_inode_operations; } static void -- cgit v1.2.3-59-g8ed1b