The patch titled
fix for futex restart patch
has been added to the -mm tree. Its filename is
futex-restartable-futex_wait-fix.patch
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: fix for futex restart patch
From: Nick Piggin <npiggin@xxxxxxx>
This uses absolute timeouts for futex restarts, so that we never lose a jiffy
during the restart. Can be folded with the other futex patch.
Cc: Ulrich Drepper <drepper@xxxxxxxxxx>
Cc: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
Cc: Roland McGrath <roland@xxxxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/futex.c | 39 +++++++++++++++++++++++++++++++--------
1 file changed, 31 insertions(+), 8 deletions(-)
diff -puN kernel/futex.c~futex-restartable-futex_wait-fix kernel/futex.c
--- a/kernel/futex.c~futex-restartable-futex_wait-fix
+++ a/kernel/futex.c
@@ -1001,12 +1001,14 @@ static void unqueue_me_pi(struct futex_q
}
static long futex_wait_restart(struct restart_block *restart);
-static int futex_wait(u32 __user *uaddr, u32 val, unsigned long time)
+static int futex_wait_abstime(u32 __user *uaddr, u32 val,
+ int timed, unsigned long abs_time)
{
struct task_struct *curr = current;
DECLARE_WAITQUEUE(wait, curr);
struct futex_hash_bucket *hb;
struct futex_q q;
+ unsigned long time_left = 0;
u32 uval;
int ret;
@@ -1086,8 +1088,21 @@ static int futex_wait(u32 __user *uaddr,
* !list_empty() is safe here without any lock.
* q.lock_ptr != 0 is not safe, because of ordering against wakeup.
*/
- if (likely(!list_empty(&q.list)))
- time = schedule_timeout(time);
+ time_left = 0;
+ if (likely(!list_empty(&q.list))) {
+ unsigned long rel_time;
+
+ if (timed) {
+ unsigned long now = jiffies;
+ if (time_after(now, abs_time))
+ rel_time = 0;
+ else
+ rel_time = abs_time - now;
+ } else
+ rel_time = MAX_SCHEDULE_TIMEOUT;
+
+ time_left = schedule_timeout(rel_time);
+ }
__set_current_state(TASK_RUNNING);
/*
@@ -1098,14 +1113,14 @@ static int futex_wait(u32 __user *uaddr,
/* If we were woken (and unqueued), we succeeded, whatever. */
if (!unqueue_me(&q))
return 0;
- if (time == 0)
+ if (time_left == 0)
return -ETIMEDOUT;
/*
* We expect signal_pending(current), but another thread may
* have handled it for us already.
*/
- if (time == MAX_SCHEDULE_TIMEOUT)
+ if (time_left == MAX_SCHEDULE_TIMEOUT)
return -ERESTARTSYS;
else {
struct restart_block *restart;
@@ -1113,7 +1128,8 @@ static int futex_wait(u32 __user *uaddr,
restart->fn = futex_wait_restart;
restart->arg0 = (unsigned long)uaddr;
restart->arg1 = (unsigned long)val;
- restart->arg2 = time;
+ restart->arg2 = (unsigned long)timed;
+ restart->arg3 = abs_time;
return -ERESTART_RESTARTBLOCK;
}
@@ -1125,14 +1141,21 @@ static int futex_wait(u32 __user *uaddr,
return ret;
}
+static int futex_wait(u32 __user *uaddr, u32 val, unsigned long rel_time)
+{
+ int timed = (rel_time != MAX_SCHEDULE_TIMEOUT);
+ return futex_wait_abstime(uaddr, val, timed, jiffies+rel_time);
+}
+
static long futex_wait_restart(struct restart_block *restart)
{
u32 __user *uaddr = (u32 __user *)restart->arg0;
u32 val = (u32)restart->arg1;
- unsigned long time = restart->arg2;
+ int timed = (int)restart->arg2;
+ unsigned long abs_time = restart->arg3;
restart->fn = do_no_restart_syscall;
- return (long)futex_wait(uaddr, val, time);
+ return (long)futex_wait_abstime(uaddr, val, timed, abs_time);
}
_
Patches currently in -mm which might be from npiggin@xxxxxxx are
mm-fix-madvise-infinine-loop.patch
futex-restartable-futex_wait.patch
futex-restartable-futex_wait-fix.patch
splice-dont-steal.patch
splice-dont-readpage.patch
mm-remove-gcc-workaround.patch
mm-more-rmap-checking.patch
mm-make-read_cache_page-synchronous.patch
fs-buffer-dont-pageuptodate-without-page-locked.patch
mm-debug-check-for-the-fault-vs-invalidate-race.patch
mm-debug-check-for-the-fault-vs-invalidate-race-tidy.patch
mm-simplify-filemap_nopage.patch
mm-fix-fault-vs-invalidate-race-for-linear-mappings.patch
mm-merge-populate-and-nopage-into-fault-fixes-nonlinear.patch
mm-merge-populate-and-nopage-into-fault-fixes-nonlinear-tidy.patch
mm-merge-nopfn-into-fault.patch
mm-remove-legacy-cruft.patch
mm-fix-clear_page_dirty_for_io-vs-fault-race.patch
exec-fix-remove_arg_zero.patch
exec-fix-remove_arg_zero-add-comment.patch
as-fix-antic_expire-check.patch
-
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