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authordann frazier <dannf@hp.com>2008-11-26 18:32:27 -0500
committerDavid S. Miller <davem@davemloft.net>2008-11-26 18:32:27 -0500
commit5f23b734963ec7eaa3ebcd9050da0c9b7d143dd3 (patch)
treef82c2265540dd5d32d64f08976cd9b6216842544
parentefbbced361f3ff4ff9e85310ccff894185c4d904 (diff)
net: Fix soft lockups/OOM issues w/ unix garbage collector
This is an implementation of David Miller's suggested fix in: https://bugzilla.redhat.com/show_bug.cgi?id=470201 It has been updated to use wait_event() instead of wait_event_interruptible(). Paraphrasing the description from the above report, it makes sendmsg() block while UNIX garbage collection is in progress. This avoids a situation where child processes continue to queue new FDs over a AF_UNIX socket to a parent which is in the exit path and running garbage collection on these FDs. This contention can result in soft lockups and oom-killing of unrelated processes. Signed-off-by: dann frazier <dannf@hp.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--include/net/af_unix.h1
-rw-r--r--net/unix/af_unix.c2
-rw-r--r--net/unix/garbage.c13
3 files changed, 13 insertions, 3 deletions
diff --git a/include/net/af_unix.h b/include/net/af_unix.h
index c29ff1da8a18..1614d78c60ed 100644
--- a/include/net/af_unix.h
+++ b/include/net/af_unix.h
@@ -9,6 +9,7 @@
9extern void unix_inflight(struct file *fp); 9extern void unix_inflight(struct file *fp);
10extern void unix_notinflight(struct file *fp); 10extern void unix_notinflight(struct file *fp);
11extern void unix_gc(void); 11extern void unix_gc(void);
12extern void wait_for_unix_gc(void);
12 13
13#define UNIX_HASH_SIZE 256 14#define UNIX_HASH_SIZE 256
14 15
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index eb90f77bb0e2..66d5ac4773ab 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -1343,6 +1343,7 @@ static int unix_dgram_sendmsg(struct kiocb *kiocb, struct socket *sock,
1343 1343
1344 if (NULL == siocb->scm) 1344 if (NULL == siocb->scm)
1345 siocb->scm = &tmp_scm; 1345 siocb->scm = &tmp_scm;
1346 wait_for_unix_gc();
1346 err = scm_send(sock, msg, siocb->scm); 1347 err = scm_send(sock, msg, siocb->scm);
1347 if (err < 0) 1348 if (err < 0)
1348 return err; 1349 return err;
@@ -1493,6 +1494,7 @@ static int unix_stream_sendmsg(struct kiocb *kiocb, struct socket *sock,
1493 1494
1494 if (NULL == siocb->scm) 1495 if (NULL == siocb->scm)
1495 siocb->scm = &tmp_scm; 1496 siocb->scm = &tmp_scm;
1497 wait_for_unix_gc();
1496 err = scm_send(sock, msg, siocb->scm); 1498 err = scm_send(sock, msg, siocb->scm);
1497 if (err < 0) 1499 if (err < 0)
1498 return err; 1500 return err;
diff --git a/net/unix/garbage.c b/net/unix/garbage.c
index 6d4a9a8de5ef..abb3ab34cb1e 100644
--- a/net/unix/garbage.c
+++ b/net/unix/garbage.c
@@ -80,6 +80,7 @@
80#include <linux/file.h> 80#include <linux/file.h>
81#include <linux/proc_fs.h> 81#include <linux/proc_fs.h>
82#include <linux/mutex.h> 82#include <linux/mutex.h>
83#include <linux/wait.h>
83 84
84#include <net/sock.h> 85#include <net/sock.h>
85#include <net/af_unix.h> 86#include <net/af_unix.h>
@@ -91,6 +92,7 @@
91static LIST_HEAD(gc_inflight_list); 92static LIST_HEAD(gc_inflight_list);
92static LIST_HEAD(gc_candidates); 93static LIST_HEAD(gc_candidates);
93static DEFINE_SPINLOCK(unix_gc_lock); 94static DEFINE_SPINLOCK(unix_gc_lock);
95static DECLARE_WAIT_QUEUE_HEAD(unix_gc_wait);
94 96
95unsigned int unix_tot_inflight; 97unsigned int unix_tot_inflight;
96 98
@@ -266,12 +268,16 @@ static void inc_inflight_move_tail(struct unix_sock *u)
266 list_move_tail(&u->link, &gc_candidates); 268 list_move_tail(&u->link, &gc_candidates);
267} 269}
268 270
269/* The external entry point: unix_gc() */ 271static bool gc_in_progress = false;
270 272
271void unix_gc(void) 273void wait_for_unix_gc(void)
272{ 274{
273 static bool gc_in_progress = false; 275 wait_event(unix_gc_wait, gc_in_progress == false);
276}
274 277
278/* The external entry point: unix_gc() */
279void unix_gc(void)
280{
275 struct unix_sock *u; 281 struct unix_sock *u;
276 struct unix_sock *next; 282 struct unix_sock *next;
277 struct sk_buff_head hitlist; 283 struct sk_buff_head hitlist;
@@ -376,6 +382,7 @@ void unix_gc(void)
376 /* All candidates should have been detached by now. */ 382 /* All candidates should have been detached by now. */
377 BUG_ON(!list_empty(&gc_candidates)); 383 BUG_ON(!list_empty(&gc_candidates));
378 gc_in_progress = false; 384 gc_in_progress = false;
385 wake_up(&unix_gc_wait);
379 386
380 out: 387 out:
381 spin_unlock(&unix_gc_lock); 388 spin_unlock(&unix_gc_lock);