linux-kernel - [PATCH 2/6] ftrace syscalls: Convert redundant syscall_nr checks into WARN

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Date:	Thu,  3 Feb 2011 14:27:21 +1100
From:	"Ian Munsie" <imunsie@....ibm.com>
To:	linux-kernel@...r.kernel.org
Cc:	Andreas Dilger <adilger@...ger.ca>,
	Dave Kleikamp <shaggy@...ux.vnet.ibm.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Jiri Kosina <jkosina@...e.cz>, Jason Baron <jbaron@...hat.com>,
	linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Alexander Graf <agraf@...e.de>, Ingo Molnar <mingo@...hat.com>,
	Paul Mackerras <paulus@...ba.org>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Scott Wood <scottwood@...escale.com>,
	Nathan Lynch <ntl@...ox.com>,
	Avantika Mathur <mathur@...ux.vnet.ibm.com>,
	David Gibson <dwg@....ibm.com>,
	Andreas Schwab <schwab@...ux-m68k.org>,
	Namhyung Kim <namhyung@...il.com>,
	Ian Munsie <imunsie@....ibm.com>
Subject: [PATCH 2/6] ftrace syscalls: Convert redundant syscall_nr checks into WARN_ON

From: Ian Munsie <imunsie@....ibm.com>

With the ftrace events now checking if the syscall_nr is valid upon
initialisation it should no longer be possible to register or unregister
a syscall event without a valid syscall_nr since they should not be
created. This adds a WARN_ON_ONCE in the register and unregister
functions to locate potential regressions in the future.

Signed-off-by: Ian Munsie <imunsie@....ibm.com>
---
 kernel/trace/trace_syscalls.c |    8 ++++----
 1 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c
index a66bc13..1a6e8dd 100644
--- a/kernel/trace/trace_syscalls.c
+++ b/kernel/trace/trace_syscalls.c
@@ -358,7 +358,7 @@ int reg_event_syscall_enter(struct ftrace_event_call *call)
 	int num;
 
 	num = ((struct syscall_metadata *)call->data)->syscall_nr;
-	if (num < 0 || num >= NR_syscalls)
+	if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))
 		return -ENOSYS;
 	mutex_lock(&syscall_trace_lock);
 	if (!sys_refcount_enter)
@@ -376,7 +376,7 @@ void unreg_event_syscall_enter(struct ftrace_event_call *call)
 	int num;
 
 	num = ((struct syscall_metadata *)call->data)->syscall_nr;
-	if (num < 0 || num >= NR_syscalls)
+	if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))
 		return;
 	mutex_lock(&syscall_trace_lock);
 	sys_refcount_enter--;
@@ -392,7 +392,7 @@ int reg_event_syscall_exit(struct ftrace_event_call *call)
 	int num;
 
 	num = ((struct syscall_metadata *)call->data)->syscall_nr;
-	if (num < 0 || num >= NR_syscalls)
+	if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))
 		return -ENOSYS;
 	mutex_lock(&syscall_trace_lock);
 	if (!sys_refcount_exit)
@@ -410,7 +410,7 @@ void unreg_event_syscall_exit(struct ftrace_event_call *call)
 	int num;
 
 	num = ((struct syscall_metadata *)call->data)->syscall_nr;
-	if (num < 0 || num >= NR_syscalls)
+	if (WARN_ON_ONCE(num < 0 || num >= NR_syscalls))
 		return;
 	mutex_lock(&syscall_trace_lock);
 	sys_refcount_exit--;
-- 
1.7.2.3

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