[PATCH 1/3] signal: turn dequeue_signal_lock() into kernel_dequeue_signal()

From: Oleg Nesterov
Date: Sat Oct 03 2015 - 14:16:53 EST


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@xxxxxxxxxx>
---
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, &current->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, &current->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, &current->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, &current->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

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