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authorChris Wright <chrisw@sous-sol.org>2007-10-16 23:27:18 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-10-17 08:42:53 -0700
commit3075d9da0b4ccc88959db30de80ebd11d2dde175 (patch)
tree7dbdcd9b5eae671864eac060ee3138a8c862c0ea /fs/select.c
parent7e341fa1f8ed25385e2321d7e5a49ce6aea2d702 (diff)
downloadlinux-3075d9da0b4ccc88959db30de80ebd11d2dde175.tar.gz
Use ERESTART_RESTARTBLOCK if poll() is interrupted by a signal
Lomesh reported poll returning EINTR during suspend/resume cycle. This is caused by the STOP/CONT cycle that the freezer uses, generating a pending signal for what in effect is an ignored signal. In general poll is a little eager in returning EINTR, when it could try not bother userspace and simply restart the syscall. Both select and ppoll do use ERESTARTNOHAND to restart the syscall. Oleg points out that simply using ERESTARTNOHAND will cause poll to restart with original timeout value. which could ultimately lead to process never returning to userspace. Instead use ERESTART_RESTARTBLOCK, and restart poll with updated timeout value. Inspired by Manfred's use ERESTARTNOHAND in poll patch. [bunk@kernel.org: do_restart_poll() can become static] Cc: Manfred Spraul <manfred@colorfullife.com> Cc: Oleg Nesterov <oleg@tv-sign.ru> Cc: Roland McGrath <roland@redhat.com> Cc: "Agarwal, Lomesh" <lomesh.agarwal@intel.com> Signed-off-by: Chris Wright <chrisw@sous-sol.org> Signed-off-by: Adrian Bunk <bunk@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/select.c')
-rw-r--r--fs/select.c31
1 files changed, 30 insertions, 1 deletions
diff --git a/fs/select.c b/fs/select.c
index e2fd58f8f1d..7dede89658f 100644
--- a/fs/select.c
+++ b/fs/select.c
@@ -714,10 +714,28 @@ out_fds:
return err;
}
+static long do_restart_poll(struct restart_block *restart_block)
+{
+ struct pollfd __user *ufds = (struct pollfd __user*)restart_block->arg0;
+ int nfds = restart_block->arg1;
+ s64 timeout = ((s64)restart_block->arg3<<32) | (s64)restart_block->arg2;
+ int ret;
+
+ ret = do_sys_poll(ufds, nfds, &timeout);
+ if (ret == -EINTR) {
+ restart_block->fn = do_restart_poll;
+ restart_block->arg2 = timeout & 0xFFFFFFFF;
+ restart_block->arg3 = (u64)timeout >> 32;
+ ret = -ERESTART_RESTARTBLOCK;
+ }
+ return ret;
+}
+
asmlinkage long sys_poll(struct pollfd __user *ufds, unsigned int nfds,
long timeout_msecs)
{
s64 timeout_jiffies;
+ int ret;
if (timeout_msecs > 0) {
#if HZ > 1000
@@ -732,7 +750,18 @@ asmlinkage long sys_poll(struct pollfd __user *ufds, unsigned int nfds,
timeout_jiffies = timeout_msecs;
}
- return do_sys_poll(ufds, nfds, &timeout_jiffies);
+ ret = do_sys_poll(ufds, nfds, &timeout_jiffies);
+ if (ret == -EINTR) {
+ struct restart_block *restart_block;
+ restart_block = &current_thread_info()->restart_block;
+ restart_block->fn = do_restart_poll;
+ restart_block->arg0 = (unsigned long)ufds;
+ restart_block->arg1 = nfds;
+ restart_block->arg2 = timeout_jiffies & 0xFFFFFFFF;
+ restart_block->arg3 = (u64)timeout_jiffies >> 32;
+ ret = -ERESTART_RESTARTBLOCK;
+ }
+ return ret;
}
#ifdef TIF_RESTORE_SIGMASK