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authorDavide Libenzi <davidel@xmailserver.org>2008-04-11 00:29:19 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2008-04-11 11:06:43 -0400
commit8d1c98b0b5c0148b519c6416e689ef6a89ffcea3 (patch)
tree904c70d4ed15dd79a003c34bad2e25cff9522420 /fs
parentd479540dbaba6f7acdb48e0242fee868c7a68116 (diff)
eventfd/kaio integration fix
Jeff Roberson discovered a race when using kaio eventfd based notifications. When it occurs it can lead tomissed wakeups and hung userspace. This patch fixes the race by moving the notification inside the spinlocked section of kaio. The operation is safe since eventfd spinlock and kaio one are unrelated. Signed-off-by: Davide Libenzi <davidel@xmailserver.org> Cc: Zach Brown <zach.brown@oracle.com> Cc: Jeff Roberson <jroberson@chesapeake.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs')
-rw-r--r--fs/aio.c17
1 files changed, 9 insertions, 8 deletions
diff --git a/fs/aio.c b/fs/aio.c
index 60a4cd4d1137..228368610dfa 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -936,14 +936,6 @@ int aio_complete(struct kiocb *iocb, long res, long res2)
936 return 1; 936 return 1;
937 } 937 }
938 938
939 /*
940 * Check if the user asked us to deliver the result through an
941 * eventfd. The eventfd_signal() function is safe to be called
942 * from IRQ context.
943 */
944 if (!IS_ERR(iocb->ki_eventfd))
945 eventfd_signal(iocb->ki_eventfd, 1);
946
947 info = &ctx->ring_info; 939 info = &ctx->ring_info;
948 940
949 /* add a completion event to the ring buffer. 941 /* add a completion event to the ring buffer.
@@ -992,6 +984,15 @@ int aio_complete(struct kiocb *iocb, long res, long res2)
992 kunmap_atomic(ring, KM_IRQ1); 984 kunmap_atomic(ring, KM_IRQ1);
993 985
994 pr_debug("added to ring %p at [%lu]\n", iocb, tail); 986 pr_debug("added to ring %p at [%lu]\n", iocb, tail);
987
988 /*
989 * Check if the user asked us to deliver the result through an
990 * eventfd. The eventfd_signal() function is safe to be called
991 * from IRQ context.
992 */
993 if (!IS_ERR(iocb->ki_eventfd))
994 eventfd_signal(iocb->ki_eventfd, 1);
995
995put_rq: 996put_rq:
996 /* everything turned out well, dispose of the aiocb. */ 997 /* everything turned out well, dispose of the aiocb. */
997 ret = __aio_put_req(ctx, iocb); 998 ret = __aio_put_req(ctx, iocb);