linux-kernel - [PATCH 2/5] mn10300: Prevent double syscall restarts

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Message-ID: <20100927104754.6377.97402.stgit@warthog.procyon.org.uk>
Date:	Mon, 27 Sep 2010 11:47:54 +0100
From:	David Howells <dhowells@...hat.com>
To:	torvalds@...l.org, akpm@...ux-foundation.org
Cc:	linux-am33-list@...hat.com, linux-kernel@...r.kernel.org,
	Al Viro <viro@...iv.linux.org.uk>,
	David Howells <dhowells@...hat.com>
Subject: [PATCH 2/5] mn10300: Prevent double syscall restarts

From: Al Viro <viro@....linux.org.uk>

We need to make sure that only the first do_signal() to be handled on
the way out of the syscall handler will bother with syscall restarts.

We do this by setting orig_d0 to -1 as sigreturn does.

Signed-off-by: Al Viro <viro@...iv.linux.org.uk>
Signed-off-by: David Howells <dhowells@...hat.com>
---

 arch/mn10300/kernel/signal.c |   12 +++++++++---
 1 files changed, 9 insertions(+), 3 deletions(-)


diff --git a/arch/mn10300/kernel/signal.c b/arch/mn10300/kernel/signal.c
index 57178a8..4ef9925 100644
--- a/arch/mn10300/kernel/signal.c
+++ b/arch/mn10300/kernel/signal.c
@@ -432,6 +432,12 @@ give_sigsegv:
 	return -EFAULT;
 }
 
+static inline void stepback(struct pt_regs *regs)
+{
+	regs->pc -= 2;
+	regs->orig_d0 = -1;
+}
+
 /*
  * handle the actual delivery of a signal to userspace
  */
@@ -459,7 +465,7 @@ static int handle_signal(int sig,
 			/* fallthrough */
 		case -ERESTARTNOINTR:
 			regs->d0 = regs->orig_d0;
-			regs->pc -= 2;
+			stepback(regs);
 		}
 	}
 
@@ -527,12 +533,12 @@ static void do_signal(struct pt_regs *regs)
 		case -ERESTARTSYS:
 		case -ERESTARTNOINTR:
 			regs->d0 = regs->orig_d0;
-			regs->pc -= 2;
+			stepback(regs);
 			break;
 
 		case -ERESTART_RESTARTBLOCK:
 			regs->d0 = __NR_restart_syscall;
-			regs->pc -= 2;
+			stepback(regs);
 			break;
 		}
 	}

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