tracing/syscalls: Convert redundant syscall_nr checks into WARN_ON

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@au1.ibm.com>
LKML-Reference: <1296703645-18718-3-git-send-email-imunsie@au1.ibm.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 4 insertions, 4 deletions

diff --git a/kernel/trace/trace_syscalls.c b/kernel/trace/trace_syscalls.c
index a9ceabd52247..423094288fb5 100644
--- a/kernel/trace/trace_syscalls.c
+++ b/kernel/trace/trace_syscalls.c
@@ -359,7 +359,7 @@ 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)
@@ -377,7 +377,7 @@ 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--;
@@ -393,7 +393,7 @@ 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)
@@ -411,7 +411,7 @@ 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--;