From: Eric Dumazet <edumazet@google.com>
Date: Tue, 24 Jan 2017 23:18:07 +0000 (-0800)
Subject: proc: add a schedule point in proc_pid_readdir()
X-Git-Url: http://git.cdn.openwrt.org/?a=commitdiff_plain;h=3ba4bceef23206349d4130ddf140819b365de7c8;p=openwrt%2Fstaging%2Fblogic.git

proc: add a schedule point in proc_pid_readdir()

We have seen proc_pid_readdir() invocations holding cpu for more than 50
ms.  Add a cond_resched() to be gentle with other tasks.

[akpm@linux-foundation.org: coding style fix]
Link: http://lkml.kernel.org/r/1484238380.15816.42.camel@edumazet-glaptop3.roam.corp.google.com
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 8e7e61b28f31..87c9a9aacda3 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -3179,6 +3179,8 @@ int proc_pid_readdir(struct file *file, struct dir_context *ctx)
 	     iter.tgid += 1, iter = next_tgid(ns, iter)) {
 		char name[PROC_NUMBUF];
 		int len;
+
+		cond_resched();
 		if (!has_pid_permissions(ns, iter.task, 2))
 			continue;