The patch titled
Subject: coredump: make wait_for_dump_helpers() freezable
has been added to the -mm tree. Its filename is
coredump-make-wait_for_dump_helpers-freezable.patch
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------------------------------------------------------
From: Oleg Nesterov <oleg@xxxxxxxxxx>
Subject: coredump: make wait_for_dump_helpers() freezable
wait_for_dump_helpers() calls wake_up/kill_fasync from inside the
wait_event-like loop. This is not needed and in fact this is not strictly
correct, we can/should do this only once after we change pipe->writers.
We could even check if it becomes zero.
With this change it is trivial to convert this code to use
wait_event_freezable() and make this function freezable/killable, only
SIGKILL can set TIF_SIGPENDING.
With this patch we check pipe->readers without pipe_lock(), this is fine.
Once we see pipe->readers == 1 we know that the handler decremented the
counter, this is all we need.
Note: wait_event_freezable() is "strange", perhaps it should be changed or
simply removed. In the latter case we can change this code again to use
freezer_do_not_count + wait_event_interruptible.
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Mandeep Singh Baines <msb@xxxxxxxxxxxx>
Cc: Neil Horman <nhorman@xxxxxxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
Cc: "Rafael J. Wysocki" <rjw@xxxxxxx>a
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/coredump.c | 12 ++++++------
1 file changed, 6 insertions(+), 6 deletions(-)
diff -puN fs/coredump.c~coredump-make-wait_for_dump_helpers-freezable fs/coredump.c
--- a/fs/coredump.c~coredump-make-wait_for_dump_helpers-freezable
+++ a/fs/coredump.c
@@ -32,6 +32,7 @@
#include <linux/pipe_fs_i.h>
#include <linux/oom.h>
#include <linux/compat.h>
+#include <linux/freezer.h>
#include <asm/uaccess.h>
#include <asm/mmu_context.h>
@@ -428,17 +429,16 @@ static void wait_for_dump_helpers(struct
pipe_lock(pipe);
pipe->readers++;
pipe->writers--;
+ wake_up_interruptible_sync(&pipe->wait);
+ kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
+ pipe_unlock(pipe);
- while ((pipe->readers > 1) && (!signal_pending(current))) {
- wake_up_interruptible_sync(&pipe->wait);
- kill_fasync(&pipe->fasync_readers, SIGIO, POLL_IN);
- pipe_wait(pipe);
- }
+ wait_event_freezable(pipe->wait, pipe->readers == 1);
+ pipe_lock(pipe);
pipe->readers--;
pipe->writers++;
pipe_unlock(pipe);
-
}
/*
_
Patches currently in -mm which might be from oleg@xxxxxxxxxx are
origin.patch
usermodehelper-cleanup-fix-__orderly_poweroff-argv_free.patch
signal-allow-to-send-any-siginfo-to-itself.patch
kernel-signalc-fix-suboptimal-printk-usage.patch
coredump-only-sigkill-should-interrupt-the-coredumping-task.patch
coredump-ensure-that-sigkill-always-kills-the-dumping-thread.patch
coredump-sanitize-the-setting-of-signal-group_exit_code.patch
coredump-factor-out-the-setting-of-pf_dumpcore.patch
freezer-do-not-send-a-fake-signal-to-a-pf_dumpcore-thread.patch
coredump-make-wait_for_dump_helpers-freezable.patch
lockdep-check-that-no-locks-held-at-freeze-time.patch
lockdep-check-that-no-locks-held-at-freeze-time-v2.patch
lockdep-check-that-no-locks-held-at-freeze-time-fix.patch
coredump-use-a-freezable_schedule-for-the-coredump_finish-wait.patch
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