* [PATCH -mm 0/3] minor kthread/signals cleanups and fix
@ 2015-10-03 18:13 Oleg Nesterov
2015-10-03 18:13 ` [PATCH 1/3] signal: turn dequeue_signal_lock() into kernel_dequeue_signal() Oleg Nesterov
` (2 more replies)
0 siblings, 3 replies; 8+ messages in thread
From: Oleg Nesterov @ 2015-10-03 18:13 UTC (permalink / raw)
To: Andrew Morton
Cc: David Woodhouse, Felipe Balbi, Markus Pargmann, Tejun Heo,
linux-kernel, linux-mtd
On top of signals-kill-block_all_signals-and-unblock_all_signals.patch
Simple but untested, hopefully maintainers can ack or nack 1/3 at least.
Oleg.
drivers/block/nbd.c | 9 ++-------
drivers/usb/gadget/function/f_mass_storage.c | 4 +---
fs/jffs2/background.c | 7 ++-----
include/linux/sched.h | 21 ++++++++++++++++-----
4 files changed, 21 insertions(+), 20 deletions(-)
^ permalink raw reply [flat|nested] 8+ messages in thread* [PATCH 1/3] signal: turn dequeue_signal_lock() into kernel_dequeue_signal() 2015-10-03 18:13 [PATCH -mm 0/3] minor kthread/signals cleanups and fix Oleg Nesterov @ 2015-10-03 18:13 ` Oleg Nesterov 2015-10-04 16:38 ` Tejun Heo 2015-10-25 13:33 ` [PATCH -mm] signal-turn-dequeue_signal_lock-into-kernel_dequeue_signal-fix Oleg Nesterov 2015-10-03 18:13 ` [PATCH 2/3] signal: introduce kernel_signal_stop() to fix jffs2_garbage_collect_thread() Oleg Nesterov 2015-10-03 18:13 ` [PATCH 3/3] signal: remove jffs2_garbage_collect_thread()->allow_signal(SIGCONT) Oleg Nesterov 2 siblings, 2 replies; 8+ messages in thread From: Oleg Nesterov @ 2015-10-03 18:13 UTC (permalink / raw) To: Andrew Morton Cc: David Woodhouse, Felipe Balbi, Markus Pargmann, Tejun Heo, linux-kernel, linux-mtd 1. Rename dequeue_signal_lock() to kernel_dequeue_signal(). This matches another "for kthreads only" kernel_sigaction() helper. 2. Remove the "tsk" and "mask" arguments, they are always current and current->blocked. And it is simply wrong if tsk != current. 3. We could also remove the 3rd "siginfo_t *info" arg but it looks potentially useful. However we can simplify the callers if we change kernel_dequeue_signal() to accept info => NULL. 4. Remove _irqsave, it is never called from atomic context. Signed-off-by: Oleg Nesterov <oleg@redhat.com> --- drivers/block/nbd.c | 9 ++------- drivers/usb/gadget/function/f_mass_storage.c | 4 +--- fs/jffs2/background.c | 3 +-- include/linux/sched.h | 11 ++++++----- 4 files changed, 10 insertions(+), 17 deletions(-) diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c index 293495a..214de17 100644 --- a/drivers/block/nbd.c +++ b/drivers/block/nbd.c @@ -432,9 +432,7 @@ static int nbd_thread_recv(struct nbd_device *nbd) nbd->task_recv = NULL; if (signal_pending(current)) { - siginfo_t info; - - ret = dequeue_signal_lock(current, ¤t->blocked, &info); + ret = kernel_dequeue_signal(NULL); dev_warn(nbd_to_dev(nbd), "pid %d, %s, got signal %d\n", task_pid_nr(current), current->comm, ret); mutex_lock(&nbd->tx_lock); @@ -545,11 +543,8 @@ static int nbd_thread_send(void *data) !list_empty(&nbd->waiting_queue)); if (signal_pending(current)) { - siginfo_t info; - int ret; + int ret = kernel_dequeue_signal(NULL); - ret = dequeue_signal_lock(current, ¤t->blocked, - &info); dev_warn(nbd_to_dev(nbd), "pid %d, %s, got signal %d\n", task_pid_nr(current), current->comm, ret); mutex_lock(&nbd->tx_lock); diff --git a/drivers/usb/gadget/function/f_mass_storage.c b/drivers/usb/gadget/function/f_mass_storage.c index a6eb537..9d1e3b3 100644 --- a/drivers/usb/gadget/function/f_mass_storage.c +++ b/drivers/usb/gadget/function/f_mass_storage.c @@ -2347,7 +2347,6 @@ static void fsg_disable(struct usb_function *f) static void handle_exception(struct fsg_common *common) { - siginfo_t info; int i; struct fsg_buffhd *bh; enum fsg_state old_state; @@ -2359,8 +2358,7 @@ static void handle_exception(struct fsg_common *common) * into a high-priority EXIT exception. */ for (;;) { - int sig = - dequeue_signal_lock(current, ¤t->blocked, &info); + int sig = kernel_dequeue_signal(NULL); if (!sig) break; if (sig != SIGUSR1) { diff --git a/fs/jffs2/background.c b/fs/jffs2/background.c index bb9cebc..f3145fd 100644 --- a/fs/jffs2/background.c +++ b/fs/jffs2/background.c @@ -121,13 +121,12 @@ static int jffs2_garbage_collect_thread(void *_c) /* Put_super will send a SIGKILL and then wait on the sem. */ while (signal_pending(current) || freezing(current)) { - siginfo_t info; unsigned long signr; if (try_to_freeze()) goto again; - signr = dequeue_signal_lock(current, ¤t->blocked, &info); + signr = kernel_dequeue_signal(NULL); switch(signr) { case SIGSTOP: diff --git a/include/linux/sched.h b/include/linux/sched.h index 8c3fa80..e714539 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -2464,14 +2464,15 @@ extern void ignore_signals(struct task_struct *); extern void flush_signal_handlers(struct task_struct *, int force_default); extern int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info); -static inline int dequeue_signal_lock(struct task_struct *tsk, sigset_t *mask, siginfo_t *info) +static inline int kernel_dequeue_signal(siginfo_t *info) { - unsigned long flags; + struct task_struct *tsk = current; + siginfo_t __info; int ret; - spin_lock_irqsave(&tsk->sighand->siglock, flags); - ret = dequeue_signal(tsk, mask, info); - spin_unlock_irqrestore(&tsk->sighand->siglock, flags); + spin_lock_irq(&tsk->sighand->siglock); + ret = dequeue_signal(tsk, &tsk->blocked, info ?: &__info); + spin_unlock_irq(&tsk->sighand->siglock); return ret; } -- 2.4.3 ^ permalink raw reply related [flat|nested] 8+ messages in thread
* Re: [PATCH 1/3] signal: turn dequeue_signal_lock() into kernel_dequeue_signal() 2015-10-03 18:13 ` [PATCH 1/3] signal: turn dequeue_signal_lock() into kernel_dequeue_signal() Oleg Nesterov @ 2015-10-04 16:38 ` Tejun Heo 2015-10-25 13:33 ` [PATCH -mm] signal-turn-dequeue_signal_lock-into-kernel_dequeue_signal-fix Oleg Nesterov 1 sibling, 0 replies; 8+ messages in thread From: Tejun Heo @ 2015-10-04 16:38 UTC (permalink / raw) To: Oleg Nesterov Cc: Andrew Morton, David Woodhouse, Felipe Balbi, Markus Pargmann, linux-kernel, linux-mtd On Sat, Oct 03, 2015 at 08:13:36PM +0200, Oleg Nesterov wrote: > 1. Rename dequeue_signal_lock() to kernel_dequeue_signal(). This > matches another "for kthreads only" kernel_sigaction() helper. > > 2. Remove the "tsk" and "mask" arguments, they are always current > and current->blocked. And it is simply wrong if tsk != current. > > 3. We could also remove the 3rd "siginfo_t *info" arg but it looks > potentially useful. However we can simplify the callers if we > change kernel_dequeue_signal() to accept info => NULL. > > 4. Remove _irqsave, it is never called from atomic context. > > Signed-off-by: Oleg Nesterov <oleg@redhat.com> FWIW, looks good to me. Reviewed-by: Tejun Heo <tj@kernel.org> Thanks. -- tejun ^ permalink raw reply [flat|nested] 8+ messages in thread
* [PATCH -mm] signal-turn-dequeue_signal_lock-into-kernel_dequeue_signal-fix 2015-10-03 18:13 ` [PATCH 1/3] signal: turn dequeue_signal_lock() into kernel_dequeue_signal() Oleg Nesterov 2015-10-04 16:38 ` Tejun Heo @ 2015-10-25 13:33 ` Oleg Nesterov 1 sibling, 0 replies; 8+ messages in thread From: Oleg Nesterov @ 2015-10-25 13:33 UTC (permalink / raw) To: Andrew Morton Cc: David Woodhouse, Felipe Balbi, Markus Pargmann, Tejun Heo, linux-kernel, linux-mtd Andrew, As Markus reports (thanks!) signal-turn-dequeue_signal_lock-into-kernel_dequeue_signal.patch conflicts with the recent change in Linus' tree, > I just realised that this patch will conflict with a fixup patch for nbd > that will be included in rc7. > > dcc909d90ccd (nbd: Add locking for tasks) > > I think there is basically one new instance of dequeue_signal_lock() that > needs to be replaced with kernel_dequeue_signal(). Unless I missed something, this new dequeue_signal_lock() should simply die, but lets fix the conflict first. --- a/drivers/block/nbd.c +++ b/drivers/block/nbd.c @@ -592,10 +592,8 @@ static int nbd_thread_send(void *data) spin_unlock_irqrestore(&nbd->tasks_lock, flags); /* Clear maybe pending signals */ - if (signal_pending(current)) { - siginfo_t info; - dequeue_signal_lock(current, ¤t->blocked, &info); - } + if (signal_pending(current)) + kernel_dequeue_signal(NULL); return 0; } ^ permalink raw reply [flat|nested] 8+ messages in thread
* [PATCH 2/3] signal: introduce kernel_signal_stop() to fix jffs2_garbage_collect_thread() 2015-10-03 18:13 [PATCH -mm 0/3] minor kthread/signals cleanups and fix Oleg Nesterov 2015-10-03 18:13 ` [PATCH 1/3] signal: turn dequeue_signal_lock() into kernel_dequeue_signal() Oleg Nesterov @ 2015-10-03 18:13 ` Oleg Nesterov 2015-10-04 17:28 ` Tejun Heo 2015-10-03 18:13 ` [PATCH 3/3] signal: remove jffs2_garbage_collect_thread()->allow_signal(SIGCONT) Oleg Nesterov 2 siblings, 1 reply; 8+ messages in thread From: Oleg Nesterov @ 2015-10-03 18:13 UTC (permalink / raw) To: Andrew Morton Cc: David Woodhouse, Felipe Balbi, Markus Pargmann, Tejun Heo, linux-kernel, linux-mtd jffs2_garbage_collect_thread() can race with SIGCONT and sleep in TASK_STOPPED state after it was already sent. Add the new helper, kernel_signal_stop(), which does this correctly. Signed-off-by: Oleg Nesterov <oleg@redhat.com> --- fs/jffs2/background.c | 3 +-- include/linux/sched.h | 10 ++++++++++ 2 files changed, 11 insertions(+), 2 deletions(-) diff --git a/fs/jffs2/background.c b/fs/jffs2/background.c index f3145fd..53cc735 100644 --- a/fs/jffs2/background.c +++ b/fs/jffs2/background.c @@ -132,8 +132,7 @@ static int jffs2_garbage_collect_thread(void *_c) case SIGSTOP: jffs2_dbg(1, "%s(): SIGSTOP received\n", __func__); - set_current_state(TASK_STOPPED); - schedule(); + kernel_signal_stop(); break; case SIGKILL: diff --git a/include/linux/sched.h b/include/linux/sched.h index e714539..56e688c 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -2477,6 +2477,16 @@ static inline int kernel_dequeue_signal(siginfo_t *info) return ret; } +static inline void kernel_signal_stop(void) +{ + spin_lock_irq(¤t->sighand->siglock); + if (current->jobctl & JOBCTL_STOP_DEQUEUED) + __set_current_state(TASK_STOPPED); + spin_unlock_irq(¤t->sighand->siglock); + + schedule(); +} + extern void release_task(struct task_struct * p); extern int send_sig_info(int, struct siginfo *, struct task_struct *); extern int force_sigsegv(int, struct task_struct *); -- 2.4.3 ^ permalink raw reply related [flat|nested] 8+ messages in thread
* Re: [PATCH 2/3] signal: introduce kernel_signal_stop() to fix jffs2_garbage_collect_thread() 2015-10-03 18:13 ` [PATCH 2/3] signal: introduce kernel_signal_stop() to fix jffs2_garbage_collect_thread() Oleg Nesterov @ 2015-10-04 17:28 ` Tejun Heo 0 siblings, 0 replies; 8+ messages in thread From: Tejun Heo @ 2015-10-04 17:28 UTC (permalink / raw) To: Oleg Nesterov Cc: Andrew Morton, David Woodhouse, Felipe Balbi, Markus Pargmann, linux-kernel, linux-mtd On Sat, Oct 03, 2015 at 08:13:38PM +0200, Oleg Nesterov wrote: > jffs2_garbage_collect_thread() can race with SIGCONT and sleep in > TASK_STOPPED state after it was already sent. Add the new helper, > kernel_signal_stop(), which does this correctly. > > Signed-off-by: Oleg Nesterov <oleg@redhat.com> Reviewed-by: Tejun Heo <tj@kernel.org> Thanks. -- tejun ^ permalink raw reply [flat|nested] 8+ messages in thread
* [PATCH 3/3] signal: remove jffs2_garbage_collect_thread()->allow_signal(SIGCONT) 2015-10-03 18:13 [PATCH -mm 0/3] minor kthread/signals cleanups and fix Oleg Nesterov 2015-10-03 18:13 ` [PATCH 1/3] signal: turn dequeue_signal_lock() into kernel_dequeue_signal() Oleg Nesterov 2015-10-03 18:13 ` [PATCH 2/3] signal: introduce kernel_signal_stop() to fix jffs2_garbage_collect_thread() Oleg Nesterov @ 2015-10-03 18:13 ` Oleg Nesterov 2015-10-04 17:28 ` Tejun Heo 2 siblings, 1 reply; 8+ messages in thread From: Oleg Nesterov @ 2015-10-03 18:13 UTC (permalink / raw) To: Andrew Morton Cc: David Woodhouse, Felipe Balbi, Markus Pargmann, Tejun Heo, linux-kernel, linux-mtd jffs2_garbage_collect_thread() does allow_signal(SIGCONT) for no reason, SIGCONT will wake a stopped task up even if it is ignored. Signed-off-by: Oleg Nesterov <oleg@redhat.com> --- fs/jffs2/background.c | 1 - 1 file changed, 1 deletion(-) diff --git a/fs/jffs2/background.c b/fs/jffs2/background.c index 53cc735..e5c1783 100644 --- a/fs/jffs2/background.c +++ b/fs/jffs2/background.c @@ -80,7 +80,6 @@ static int jffs2_garbage_collect_thread(void *_c) siginitset(&hupmask, sigmask(SIGHUP)); allow_signal(SIGKILL); allow_signal(SIGSTOP); - allow_signal(SIGCONT); allow_signal(SIGHUP); c->gc_task = current; -- 2.4.3 ^ permalink raw reply related [flat|nested] 8+ messages in thread
* Re: [PATCH 3/3] signal: remove jffs2_garbage_collect_thread()->allow_signal(SIGCONT) 2015-10-03 18:13 ` [PATCH 3/3] signal: remove jffs2_garbage_collect_thread()->allow_signal(SIGCONT) Oleg Nesterov @ 2015-10-04 17:28 ` Tejun Heo 0 siblings, 0 replies; 8+ messages in thread From: Tejun Heo @ 2015-10-04 17:28 UTC (permalink / raw) To: Oleg Nesterov Cc: Andrew Morton, David Woodhouse, Felipe Balbi, Markus Pargmann, linux-kernel, linux-mtd On Sat, Oct 03, 2015 at 08:13:41PM +0200, Oleg Nesterov wrote: > jffs2_garbage_collect_thread() does allow_signal(SIGCONT) for no reason, > SIGCONT will wake a stopped task up even if it is ignored. > > Signed-off-by: Oleg Nesterov <oleg@redhat.com> Reviewed-by: Tejun Heo <tj@kernel.org> Thanks. -- tejun ^ permalink raw reply [flat|nested] 8+ messages in thread
end of thread, other threads:[~2015-10-25 12:37 UTC | newest] Thread overview: 8+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2015-10-03 18:13 [PATCH -mm 0/3] minor kthread/signals cleanups and fix Oleg Nesterov 2015-10-03 18:13 ` [PATCH 1/3] signal: turn dequeue_signal_lock() into kernel_dequeue_signal() Oleg Nesterov 2015-10-04 16:38 ` Tejun Heo 2015-10-25 13:33 ` [PATCH -mm] signal-turn-dequeue_signal_lock-into-kernel_dequeue_signal-fix Oleg Nesterov 2015-10-03 18:13 ` [PATCH 2/3] signal: introduce kernel_signal_stop() to fix jffs2_garbage_collect_thread() Oleg Nesterov 2015-10-04 17:28 ` Tejun Heo 2015-10-03 18:13 ` [PATCH 3/3] signal: remove jffs2_garbage_collect_thread()->allow_signal(SIGCONT) Oleg Nesterov 2015-10-04 17:28 ` Tejun Heo
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