net: fix napi_disable() logic error

Dan reported a new warning after my recent patch:

New smatch warnings:
net/core/dev.c:6409 napi_disable() error: uninitialized symbol 'new'.

Indeed, we must first wait for STATE_SCHED and STATE_NPSVC to be cleared,
to make sure @new variable has been initialized properly.

Fixes: 4ffa1d1c6842 ("net: adopt try_cmpxchg() in napi_{enable|disable}()")
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <error27@gmail.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/core/dev.c b/net/core/dev.c
index d0fb4af..7627c47 100644 (file)
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -6399,9 +6399,9 @@ void napi_disable(struct napi_struct *n)
 
        val = READ_ONCE(n->state);
        do {
-               if (val & (NAPIF_STATE_SCHED | NAPIF_STATE_NPSVC)) {
+               while (val & (NAPIF_STATE_SCHED | NAPIF_STATE_NPSVC)) {
                        usleep_range(20, 200);
-                       continue;
+                       val = READ_ONCE(n->state);
                }
 
                new = val | NAPIF_STATE_SCHED | NAPIF_STATE_NPSVC;