linux-kernel - [PATCH] nbd.c:sock_xmit: cleanup signal related code

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Date:	Thu, 14 Jun 2007 21:22:43 +0400
From:	Oleg Nesterov <oleg@...sign.ru>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Paul Clements <Paul.Clements@...eleye.com>,
	Pavel Machek <pavel@....cz>,
	Roland McGrath <roland@...hat.com>,
	linux-kernel@...r.kernel.org
Subject: [PATCH] nbd.c:sock_xmit: cleanup signal related code

sock_xmit() re-implements sigprocmask() and dequeue_signal_lock().

Note: I can't understand this dequeue_signal(), it can dequeue SIGKILL
for the user-space task doing nbd_ioctl() ?

Signed-off-by: Oleg Nesterov <oleg@...sign.ru>

--- sig/drivers/block/nbd.c~1_nbd	2007-05-21 13:57:50.000000000 +0400
+++ sig/drivers/block/nbd.c	2007-06-14 19:39:55.000000000 +0400
@@ -122,17 +122,12 @@ static int sock_xmit(struct socket *sock
 	int result;
 	struct msghdr msg;
 	struct kvec iov;
-	unsigned long flags;
-	sigset_t oldset;
+	sigset_t blocked, oldset;
 
 	/* Allow interception of SIGKILL only
 	 * Don't allow other signals to interrupt the transmission */
-	spin_lock_irqsave(&current->sighand->siglock, flags);
-	oldset = current->blocked;
-	sigfillset(&current->blocked);
-	sigdelsetmask(&current->blocked, sigmask(SIGKILL));
-	recalc_sigpending();
-	spin_unlock_irqrestore(&current->sighand->siglock, flags);
+	siginitsetinv(&blocked, sigmask(SIGKILL));
+	sigprocmask(SIG_SETMASK, &blocked, &oldset);
 
 	do {
 		sock->sk->sk_allocation = GFP_NOIO;
@@ -151,11 +146,9 @@ static int sock_xmit(struct socket *sock
 
 		if (signal_pending(current)) {
 			siginfo_t info;
-			spin_lock_irqsave(&current->sighand->siglock, flags);
 			printk(KERN_WARNING "nbd (pid %d: %s) got signal %d\n",
-				current->pid, current->comm, 
-				dequeue_signal(current, &current->blocked, &info));
-			spin_unlock_irqrestore(&current->sighand->siglock, flags);
+				current->pid, current->comm,
+				dequeue_signal_lock(current, &current->blocked, &info));
 			result = -EINTR;
 			break;
 		}
@@ -169,10 +162,7 @@ static int sock_xmit(struct socket *sock
 		buf += result;
 	} while (size > 0);
 
-	spin_lock_irqsave(&current->sighand->siglock, flags);
-	current->blocked = oldset;
-	recalc_sigpending();
-	spin_unlock_irqrestore(&current->sighand->siglock, flags);
+	sigprocmask(SIG_SETMASK, &oldset, NULL);
 
 	return result;
 }

-
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