diff options
Diffstat (limited to 'kernel/trace/trace.c')
| -rw-r--r-- | kernel/trace/trace.c | 225 |
1 files changed, 214 insertions, 11 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index c4238b441624..94ffc1c559d5 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -894,7 +894,7 @@ int __trace_bputs(unsigned long ip, const char *str) EXPORT_SYMBOL_GPL(__trace_bputs); #ifdef CONFIG_TRACER_SNAPSHOT -void tracing_snapshot_instance(struct trace_array *tr) +void tracing_snapshot_instance_cond(struct trace_array *tr, void *cond_data) { struct tracer *tracer = tr->current_trace; unsigned long flags; @@ -920,10 +920,15 @@ void tracing_snapshot_instance(struct trace_array *tr) } local_irq_save(flags); - update_max_tr(tr, current, smp_processor_id()); + update_max_tr(tr, current, smp_processor_id(), cond_data); local_irq_restore(flags); } +void tracing_snapshot_instance(struct trace_array *tr) +{ + tracing_snapshot_instance_cond(tr, NULL); +} + /** * tracing_snapshot - take a snapshot of the current buffer. * @@ -946,6 +951,54 @@ void tracing_snapshot(void) } EXPORT_SYMBOL_GPL(tracing_snapshot); +/** + * tracing_snapshot_cond - conditionally take a snapshot of the current buffer. + * @tr: The tracing instance to snapshot + * @cond_data: The data to be tested conditionally, and possibly saved + * + * This is the same as tracing_snapshot() except that the snapshot is + * conditional - the snapshot will only happen if the + * cond_snapshot.update() implementation receiving the cond_data + * returns true, which means that the trace array's cond_snapshot + * update() operation used the cond_data to determine whether the + * snapshot should be taken, and if it was, presumably saved it along + * with the snapshot. + */ +void tracing_snapshot_cond(struct trace_array *tr, void *cond_data) +{ + tracing_snapshot_instance_cond(tr, cond_data); +} +EXPORT_SYMBOL_GPL(tracing_snapshot_cond); + +/** + * tracing_snapshot_cond_data - get the user data associated with a snapshot + * @tr: The tracing instance + * + * When the user enables a conditional snapshot using + * tracing_snapshot_cond_enable(), the user-defined cond_data is saved + * with the snapshot. This accessor is used to retrieve it. + * + * Should not be called from cond_snapshot.update(), since it takes + * the tr->max_lock lock, which the code calling + * cond_snapshot.update() has already done. + * + * Returns the cond_data associated with the trace array's snapshot. + */ +void *tracing_cond_snapshot_data(struct trace_array *tr) +{ + void *cond_data = NULL; + + arch_spin_lock(&tr->max_lock); + + if (tr->cond_snapshot) + cond_data = tr->cond_snapshot->cond_data; + + arch_spin_unlock(&tr->max_lock); + + return cond_data; +} +EXPORT_SYMBOL_GPL(tracing_cond_snapshot_data); + static int resize_buffer_duplicate_size(struct trace_buffer *trace_buf, struct trace_buffer *size_buf, int cpu_id); static void set_buffer_entries(struct trace_buffer *buf, unsigned long val); @@ -1025,12 +1078,111 @@ void tracing_snapshot_alloc(void) tracing_snapshot(); } EXPORT_SYMBOL_GPL(tracing_snapshot_alloc); + +/** + * tracing_snapshot_cond_enable - enable conditional snapshot for an instance + * @tr: The tracing instance + * @cond_data: User data to associate with the snapshot + * @update: Implementation of the cond_snapshot update function + * + * Check whether the conditional snapshot for the given instance has + * already been enabled, or if the current tracer is already using a + * snapshot; if so, return -EBUSY, else create a cond_snapshot and + * save the cond_data and update function inside. + * + * Returns 0 if successful, error otherwise. + */ +int tracing_snapshot_cond_enable(struct trace_array *tr, void *cond_data, + cond_update_fn_t update) +{ + struct cond_snapshot *cond_snapshot; + int ret = 0; + + cond_snapshot = kzalloc(sizeof(*cond_snapshot), GFP_KERNEL); + if (!cond_snapshot) + return -ENOMEM; + + cond_snapshot->cond_data = cond_data; + cond_snapshot->update = update; + + mutex_lock(&trace_types_lock); + + ret = tracing_alloc_snapshot_instance(tr); + if (ret) + goto fail_unlock; + + if (tr->current_trace->use_max_tr) { + ret = -EBUSY; + goto fail_unlock; + } + + /* + * The cond_snapshot can only change to NULL without the + * trace_types_lock. We don't care if we race with it going + * to NULL, but we want to make sure that it's not set to + * something other than NULL when we get here, which we can + * do safely with only holding the trace_types_lock and not + * having to take the max_lock. + */ + if (tr->cond_snapshot) { + ret = -EBUSY; + goto fail_unlock; + } + + arch_spin_lock(&tr->max_lock); + tr->cond_snapshot = cond_snapshot; + arch_spin_unlock(&tr->max_lock); + + mutex_unlock(&trace_types_lock); + + return ret; + + fail_unlock: + mutex_unlock(&trace_types_lock); + kfree(cond_snapshot); + return ret; +} +EXPORT_SYMBOL_GPL(tracing_snapshot_cond_enable); + +/** + * tracing_snapshot_cond_disable - disable conditional snapshot for an instance + * @tr: The tracing instance + * + * Check whether the conditional snapshot for the given instance is + * enabled; if so, free the cond_snapshot associated with it, + * otherwise return -EINVAL. + * + * Returns 0 if successful, error otherwise. + */ +int tracing_snapshot_cond_disable(struct trace_array *tr) +{ + int ret = 0; + + arch_spin_lock(&tr->max_lock); + + if (!tr->cond_snapshot) + ret = -EINVAL; + else { + kfree(tr->cond_snapshot); + tr->cond_snapshot = NULL; + } + + arch_spin_unlock(&tr->max_lock); + + return ret; +} +EXPORT_SYMBOL_GPL(tracing_snapshot_cond_disable); #else void tracing_snapshot(void) { WARN_ONCE(1, "Snapshot feature not enabled, but internal snapshot used"); } EXPORT_SYMBOL_GPL(tracing_snapshot); +void tracing_snapshot_cond(struct trace_array *tr, void *cond_data) +{ + WARN_ONCE(1, "Snapshot feature not enabled, but internal conditional snapshot used"); +} +EXPORT_SYMBOL_GPL(tracing_snapshot_cond); int tracing_alloc_snapshot(void) { WARN_ONCE(1, "Snapshot feature not enabled, but snapshot allocation used"); @@ -1043,6 +1195,21 @@ void tracing_snapshot_alloc(void) tracing_snapshot(); } EXPORT_SYMBOL_GPL(tracing_snapshot_alloc); +void *tracing_cond_snapshot_data(struct trace_array *tr) +{ + return NULL; +} +EXPORT_SYMBOL_GPL(tracing_cond_snapshot_data); +int tracing_snapshot_cond_enable(struct trace_array *tr, void *cond_data, cond_update_fn_t update) +{ + return -ENODEV; +} +EXPORT_SYMBOL_GPL(tracing_snapshot_cond_enable); +int tracing_snapshot_cond_disable(struct trace_array *tr) +{ + return false; +} +EXPORT_SYMBOL_GPL(tracing_snapshot_cond_disable); #endif /* CONFIG_TRACER_SNAPSHOT */ void tracer_tracing_off(struct trace_array *tr) @@ -1330,7 +1497,7 @@ __update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu) max_data->critical_start = data->critical_start; max_data->critical_end = data->critical_end; - memcpy(max_data->comm, tsk->comm, TASK_COMM_LEN); + strncpy(max_data->comm, tsk->comm, TASK_COMM_LEN); max_data->pid = tsk->pid; /* * If tsk == current, then use current_uid(), as that does not use @@ -1354,12 +1521,14 @@ __update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu) * @tr: tracer * @tsk: the task with the latency * @cpu: The cpu that initiated the trace. + * @cond_data: User data associated with a conditional snapshot * * Flip the buffers between the @tr and the max_tr and record information * about which task was the cause of this latency. */ void -update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu) +update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu, + void *cond_data) { if (tr->stop_count) return; @@ -1380,9 +1549,15 @@ update_max_tr(struct trace_array *tr, struct task_struct *tsk, int cpu) else ring_buffer_record_off(tr->max_buffer.buffer); +#ifdef CONFIG_TRACER_SNAPSHOT + if (tr->cond_snapshot && !tr->cond_snapshot->update(tr, cond_data)) + goto out_unlock; +#endif swap(tr->trace_buffer.buffer, tr->max_buffer.buffer); __update_max_tr(tr, tsk, cpu); + + out_unlock: arch_spin_unlock(&tr->max_lock); } @@ -1748,7 +1923,7 @@ static inline char *get_saved_cmdlines(int idx) static inline void set_cmdline(int idx, const char *cmdline) { - memcpy(get_saved_cmdlines(idx), cmdline, TASK_COMM_LEN); + strncpy(get_saved_cmdlines(idx), cmdline, TASK_COMM_LEN); } static int allocate_cmdlines_buffer(unsigned int val, @@ -4702,6 +4877,7 @@ static const char readme_msg[] = "\t [:size=#entries]\n" "\t [:pause][:continue][:clear]\n" "\t [:name=histname1]\n" + "\t [:<handler>.<action>]\n" "\t [if <filter>]\n\n" "\t When a matching event is hit, an entry is added to a hash\n" "\t table using the key(s) and value(s) named, and the value of a\n" @@ -4742,8 +4918,21 @@ static const char readme_msg[] = "\t unchanged.\n\n" "\t The enable_hist and disable_hist triggers can be used to\n" "\t have one event conditionally start and stop another event's\n" - "\t already-attached hist trigger. The syntax is analagous to\n" - "\t the enable_event and disable_event triggers.\n" + "\t already-attached hist trigger. The syntax is analogous to\n" + "\t the enable_event and disable_event triggers.\n\n" + "\t Hist trigger handlers and actions are executed whenever a\n" + "\t a histogram entry is added or updated. They take the form:\n\n" + "\t <handler>.<action>\n\n" + "\t The available handlers are:\n\n" + "\t onmatch(matching.event) - invoke on addition or update\n" + "\t onmax(var) - invoke if var exceeds current max\n" + "\t onchange(var) - invoke action if var changes\n\n" + "\t The available actions are:\n\n" + "\t trace(<synthetic_event>,param list) - generate synthetic event\n" + "\t save(field,...) - save current event fields\n" +#ifdef CONFIG_TRACER_SNAPSHOT + "\t snapshot() - snapshot the trace buffer\n" +#endif #endif ; @@ -5388,6 +5577,16 @@ static int tracing_set_tracer(struct trace_array *tr, const char *buf) if (t == tr->current_trace) goto out; +#ifdef CONFIG_TRACER_SNAPSHOT + if (t->use_max_tr) { + arch_spin_lock(&tr->max_lock); + if (tr->cond_snapshot) + ret = -EBUSY; + arch_spin_unlock(&tr->max_lock); + if (ret) + goto out; + } +#endif /* Some tracers won't work on kernel command line */ if (system_state < SYSTEM_RUNNING && t->noboot) { pr_warn("Tracer '%s' is not allowed on command line, ignored\n", @@ -5626,7 +5825,6 @@ out: return ret; fail: - kfree(iter->trace); kfree(iter); __trace_array_put(tr); mutex_unlock(&trace_types_lock); @@ -5825,7 +6023,6 @@ static void tracing_spd_release_pipe(struct splice_pipe_desc *spd, } static const struct pipe_buf_operations tracing_pipe_buf_ops = { - .can_merge = 0, .confirm = generic_pipe_buf_confirm, .release = generic_pipe_buf_release, .steal = generic_pipe_buf_steal, @@ -6470,6 +6667,13 @@ tracing_snapshot_write(struct file *filp, const char __user *ubuf, size_t cnt, goto out; } + arch_spin_lock(&tr->max_lock); + if (tr->cond_snapshot) + ret = -EBUSY; + arch_spin_unlock(&tr->max_lock); + if (ret) + goto out; + switch (val) { case 0: if (iter->cpu_file != RING_BUFFER_ALL_CPUS) { @@ -6495,7 +6699,7 @@ tracing_snapshot_write(struct file *filp, const char __user *ubuf, size_t cnt, local_irq_disable(); /* Now, we're going to swap */ if (iter->cpu_file == RING_BUFFER_ALL_CPUS) - update_max_tr(tr, current, smp_processor_id()); + update_max_tr(tr, current, smp_processor_id(), NULL); else update_max_tr_single(tr, current, iter->cpu_file); local_irq_enable(); @@ -6845,7 +7049,6 @@ static void buffer_pipe_buf_get(struct pipe_inode_info *pipe, /* Pipe buffer operations for a buffer. */ static const struct pipe_buf_operations buffer_pipe_buf_ops = { - .can_merge = 0, .confirm = generic_pipe_buf_confirm, .release = buffer_pipe_buf_release, .steal = generic_pipe_buf_steal, |