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authordann frazier <dannf@hp.com>2008-11-26 15:32:27 -0800
committerDavid S. Miller <davem@davemloft.net>2008-11-26 15:32:27 -0800
commit5f23b734963ec7eaa3ebcd9050da0c9b7d143dd3 (patch)
treef82c2265540dd5d32d64f08976cd9b6216842544
parentefbbced361f3ff4ff9e85310ccff894185c4d904 (diff)
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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 @@
extern void unix_inflight(struct file *fp);
extern void unix_notinflight(struct file *fp);
extern void unix_gc(void);
+extern void wait_for_unix_gc(void);
#define UNIX_HASH_SIZE 256
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,
if (NULL == siocb->scm)
siocb->scm = &tmp_scm;
+ wait_for_unix_gc();
err = scm_send(sock, msg, siocb->scm);
if (err < 0)
return err;
@@ -1493,6 +1494,7 @@ static int unix_stream_sendmsg(struct kiocb *kiocb, struct socket *sock,
if (NULL == siocb->scm)
siocb->scm = &tmp_scm;
+ wait_for_unix_gc();
err = scm_send(sock, msg, siocb->scm);
if (err < 0)
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 @@
#include <linux/file.h>
#include <linux/proc_fs.h>
#include <linux/mutex.h>
+#include <linux/wait.h>
#include <net/sock.h>
#include <net/af_unix.h>
@@ -91,6 +92,7 @@
static LIST_HEAD(gc_inflight_list);
static LIST_HEAD(gc_candidates);
static DEFINE_SPINLOCK(unix_gc_lock);
+static DECLARE_WAIT_QUEUE_HEAD(unix_gc_wait);
unsigned int unix_tot_inflight;
@@ -266,12 +268,16 @@ static void inc_inflight_move_tail(struct unix_sock *u)
list_move_tail(&u->link, &gc_candidates);
}
-/* The external entry point: unix_gc() */
+static bool gc_in_progress = false;
-void unix_gc(void)
+void wait_for_unix_gc(void)
{
- static bool gc_in_progress = false;
+ wait_event(unix_gc_wait, gc_in_progress == false);
+}
+/* The external entry point: unix_gc() */
+void unix_gc(void)
+{
struct unix_sock *u;
struct unix_sock *next;
struct sk_buff_head hitlist;
@@ -376,6 +382,7 @@ void unix_gc(void)
/* All candidates should have been detached by now. */
BUG_ON(!list_empty(&gc_candidates));
gc_in_progress = false;
+ wake_up(&unix_gc_wait);
out:
spin_unlock(&unix_gc_lock);
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