diff options
| author |   Alexey Dobriyan <adobriyan@gmail.com> | 2022-07-23 20:09:07 +0300 |
|---|---|---|
| committer |   akpm <akpm@linux-foundation.org> | 2022-07-29 18:12:35 -0700 |
| commit | ed8fb78d7ecdeb3e2e86df0027e2c2cc55f9908b (patch) | |
| tree | 7f920e6a5a183ce4b9c4ab5df660fb08ae64541e | |
| parent | bdi: remove enum wb_congested_state (diff) | |
| download | linux-dev-ed8fb78d7ecdeb3e2e86df0027e2c2cc55f9908b.tar.xz linux-dev-ed8fb78d7ecdeb3e2e86df0027e2c2cc55f9908b.zip | |
proc: add some (hopefully) insightful comments
* /proc/${pid}/net status
* removing PDE vs last close stuff (again!)
* random small stuff
Link: https://lkml.kernel.org/r/YtwrM6sDC0OQ53YB@localhost.localdomain
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
| -rw-r--r-- | fs/proc/array.c | 4 | ||||
| -rw-r--r-- | fs/proc/inode.c | 17 | ||||
| -rw-r--r-- | fs/proc/proc_net.c | 6 | ||||
| -rw-r--r-- | fs/proc/root.c | 5 |
4 files changed, 27 insertions, 5 deletions
diff --git a/fs/proc/array.c b/fs/proc/array.c index 65fa603422e0..99fcbfda8e25 100644 --- a/fs/proc/array.c +++ b/fs/proc/array.c @@ -99,6 +99,10 @@ void proc_task_name(struct seq_file *m, struct task_struct *p, bool escape) { char tcomm[64]; + /* + * Test before PF_KTHREAD because all workqueue worker threads are + * kernel threads. + */ if (p->flags & PF_WQ_WORKER) wq_worker_comm(tcomm, sizeof(tcomm), p); else if (p->flags & PF_KTHREAD) diff --git a/fs/proc/inode.c b/fs/proc/inode.c index fd40d60169b5..f130499ad843 100644 --- a/fs/proc/inode.c +++ b/fs/proc/inode.c @@ -212,7 +212,15 @@ static void unuse_pde(struct proc_dir_entry *pde) complete(pde->pde_unload_completion); } -/* pde is locked on entry, unlocked on exit */ +/* + * At most 2 contexts can enter this function: the one doing the last + * close on the descriptor and whoever is deleting PDE itself. + * + * First to enter calls ->proc_release hook and signals its completion + * to the second one which waits and then does nothing. + * + * PDE is locked on entry, unlocked on exit. + */ static void close_pdeo(struct proc_dir_entry *pde, struct pde_opener *pdeo) __releases(&pde->pde_unload_lock) { @@ -222,9 +230,6 @@ static void close_pdeo(struct proc_dir_entry *pde, struct pde_opener *pdeo) * * rmmod (remove_proc_entry() et al) can't delete an entry and proceed: * "struct file" needs to be available at the right moment. - * - * Therefore, first process to enter this function does ->release() and - * signals its completion to the other process which does nothing. */ if (pdeo->closing) { /* somebody else is doing that, just wait */ @@ -238,10 +243,12 @@ static void close_pdeo(struct proc_dir_entry *pde, struct pde_opener *pdeo) pdeo->closing = true; spin_unlock(&pde->pde_unload_lock); + file = pdeo->file; pde->proc_ops->proc_release(file_inode(file), file); + spin_lock(&pde->pde_unload_lock); - /* After ->release. */ + /* Strictly after ->proc_release, see above. */ list_del(&pdeo->lh); c = pdeo->c; spin_unlock(&pde->pde_unload_lock); diff --git a/fs/proc/proc_net.c b/fs/proc/proc_net.c index bbce6fbe779c..856839b8ae8b 100644 --- a/fs/proc/proc_net.c +++ b/fs/proc/proc_net.c @@ -350,6 +350,12 @@ static __net_init int proc_net_ns_init(struct net *net) kgid_t gid; int err; + /* + * This PDE acts only as an anchor for /proc/${pid}/net hierarchy. + * Corresponding inode (PDE(inode) == net->proc_net) is never + * instantiated therefore blanket zeroing is fine. + * net->proc_net_stat inode is instantiated normally. + */ err = -ENOMEM; netd = kmem_cache_zalloc(proc_dir_entry_cache, GFP_KERNEL); if (!netd) diff --git a/fs/proc/root.c b/fs/proc/root.c index 5a7d15d197f8..3c2ee3eb1138 100644 --- a/fs/proc/root.c +++ b/fs/proc/root.c @@ -302,6 +302,11 @@ void __init proc_root_init(void) proc_mkdir("bus", NULL); proc_sys_init(); + /* + * Last things last. It is not like userspace processes eager + * to open /proc files exist at this point but register last + * anyway. + */ register_filesystem(&proc_fs_type); } |