Commit ed8fb78d authored by Alexey Dobriyan's avatar Alexey Dobriyan Committed by Andrew Morton
Browse files

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: default avatarAlexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent fa7d574b

fs/proc/array.c

+4 −0
Original line number Diff line number Diff line
@@ -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)

fs/proc/inode.c

+12 −5
Original line number Diff line number Diff line
@@ -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);

fs/proc/proc_net.c

+6 −0
Original line number Diff line number Diff line
@@ -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)

fs/proc/root.c

+5 −0
Original line number Diff line number Diff line
@@ -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);

}