ipc: always handle a new value of auto_msgmni

proc_dointvec_minmax() returns zero if a new value has been set.  So we
don't need to check all charecters have been handled.

Below you can find two examples.  In the new value has not been handled
properly.

$ strace ./a.out
open("/proc/sys/kernel/auto_msgmni", O_WRONLY) = 3
write(3, "0\n\0", 3)                    = 2
close(3)                                = 0
exit_group(0)
$ cat /sys/kernel/debug/tracing/trace

$strace ./a.out
open("/proc/sys/kernel/auto_msgmni", O_WRONLY) = 3
write(3, "0\n", 2)                      = 2
close(3)                                = 0

$ cat /sys/kernel/debug/tracing/trace
a.out-697   [000] ....  3280.998235: unregister_ipcns_notifier <-proc_ipcauto_dointvec_minmax

Fixes: 9eefe520c814 ("ipc: do not use a negative value to re-enable msgmni automatic recomputin")
Signed-off-by: Andrey Vagin <avagin@openvz.org>
Cc: Mathias Krause <minipli@googlemail.com>
Cc: Manfred Spraul <manfred@colorfullife.com>
Cc: Joe Perches <joe@perches.com>
Cc: Davidlohr Bueso <davidlohr@hp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/ipc/ipc_sysctl.c b/ipc/ipc_sysctl.c
index c3f0326e98db1ca9a4e0afe8e494b857992ca851..e8075b24749775f254c4d821ea1fb2c4a8a4c5f1 100644 (file)
--- a/ipc/ipc_sysctl.c
+++ b/ipc/ipc_sysctl.c
@@ -123,7 +123,6 @@ static int proc_ipcauto_dointvec_minmax(struct ctl_table *table, int write,
        void __user *buffer, size_t *lenp, loff_t *ppos)
 {
        struct ctl_table ipc_table;
-       size_t lenp_bef = *lenp;
        int oldval;
        int rc;
 
@@ -133,7 +132,7 @@ static int proc_ipcauto_dointvec_minmax(struct ctl_table *table, int write,
 
        rc = proc_dointvec_minmax(&ipc_table, write, buffer, lenp, ppos);
 
-       if (write && !rc && lenp_bef == *lenp) {
+       if (write && !rc) {
                int newval = *((int *)(ipc_table.data));
                /*
                 * The file "auto_msgmni" has correctly been set.