Subject: [to-be-updated] relay-fix-timer-madness.patch removed from -mm tree
To: mingo@xxxxxxx,axboe@xxxxxxxxx,edumazet@xxxxxxxxxx,jovi.zhangwei@xxxxxxxxxx,rostedt@xxxxxxxxxxx,viro@xxxxxxxxxxxxxxxxxx,mm-commits@xxxxxxxxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Tue, 30 Jul 2013 15:43:59 -0700
The patch titled
Subject: relay: fix timer madness
has been removed from the -mm tree. Its filename was
relay-fix-timer-madness.patch
This patch was dropped because an updated version will be merged
------------------------------------------------------
From: Ingo Molnar <mingo@xxxxxxx>
Subject: relay: fix timer madness
When I'm using below ktap script to trace all event tracepoints, without
this patch, the system will hang in few seconds, the patch indeed fix the
problem as the changelog pointed.
function eventfun (e) {
printf("%d %d\t%s\t%s", cpu(), pid(), execname(), e.annotate)
}
kdebug.probe("tp:", eventfun)
kdebug.probe_end(function () {
printf("probe end\n")
})
This patch is old, I can found the original patch discussion in 2007.
http://marc.info/?l=linux-kernel&m=118544794717162&w=2 (In that mail
thread, the patch didn't fix that problem, but it fix the problem I
encountered now)
Ingo's original changelog:
Remove timer calls (!!!) from deep within the tracing infrastructure.
This was totally bogus code that can cause lockups and worse.
Poll the buffer every 2 jiffies for now.
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
Signed-off-by: "zhangwei(Jovi)" <jovi.zhangwei@xxxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Jens Axboe <axboe@xxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Eric Dumazet <edumazet@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/relay.c | 14 +++++---------
1 file changed, 5 insertions(+), 9 deletions(-)
diff -puN kernel/relay.c~relay-fix-timer-madness kernel/relay.c
--- a/kernel/relay.c~relay-fix-timer-madness
+++ a/kernel/relay.c
@@ -339,6 +339,10 @@ static void wakeup_readers(unsigned long
{
struct rchan_buf *buf = (struct rchan_buf *)data;
wake_up_interruptible(&buf->read_wait);
+ /*
+ * Stupid polling for now:
+ */
+ mod_timer(&buf->timer, jiffies + 1);
}
/**
@@ -356,6 +360,7 @@ static void __relay_reset(struct rchan_b
init_waitqueue_head(&buf->read_wait);
kref_init(&buf->kref);
setup_timer(&buf->timer, wakeup_readers, (unsigned long)buf);
+ mod_timer(&buf->timer, jiffies + 1);
} else
del_timer_sync(&buf->timer);
@@ -739,15 +744,6 @@ size_t relay_switch_subbuf(struct rchan_
else
buf->early_bytes += buf->chan->subbuf_size -
buf->padding[old_subbuf];
- smp_mb();
- if (waitqueue_active(&buf->read_wait))
- /*
- * Calling wake_up_interruptible() from here
- * will deadlock if we happen to be logging
- * from the scheduler (trying to re-grab
- * rq->lock), so defer it.
- */
- mod_timer(&buf->timer, jiffies + 1);
}
old = buf->data;
_
Patches currently in -mm which might be from mingo@xxxxxxx are
include-linux-schedh-dont-use-task-pid-tgid-in-same_thread_group-has_group_leader_pid.patch
watchdog-trigger-all-cpu-backtrace-when-locked-up-and-going-to-panic.patch
mm-vmstats-tlb-flush-counters.patch
mm-vmstats-track-tlb-flush-stats-on-up-too.patch
mm-hotplug-x86-disable-arch_memory_probe-by-default.patch
kernel-spinlockc-add-default-arch__relax-definitions-for-generic_lockbreak.patch
smp-give-warning-when-calling-smp_call_function_many-single-in-serving-irq.patch
relay-fix-timer-madness-v2.patch
linux-next.patch
debugging-keep-track-of-page-owners.patch
debugging-keep-track-of-page-owners-fix.patch
make-frame_pointer-default=y.patch
mutex-subsystem-synchro-test-module.patch
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