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

[Oleg Nesterov]

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 <o...@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, &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

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/