From facc432faa59414bd7c60c307ff1645154a66c98 Mon Sep 17 00:00:00 2001 From: Arnd Bergmann Date: Fri, 22 Jan 2016 11:43:44 +0100 Subject: [PATCH] net: simplify napi_synchronize() to avoid warnings The napi_synchronize() function is defined twice: The definition for SMP builds waits for other CPUs to be done, while the uniprocessor variant just contains a barrier and ignores its argument. In the mvneta driver, this leads to a warning about an unused variable when we lookup the NAPI struct of another CPU and then don't use it: ethernet/marvell/mvneta.c: In function 'mvneta_percpu_notifier': ethernet/marvell/mvneta.c:2910:30: error: unused variable 'other_port' [-Werror=unused-variable] There are no other CPUs on a UP build, so that code never runs, but gcc does not know this. The nicest solution seems to be to turn the napi_synchronize() helper into an inline function for the UP case as well, as that leads gcc to not complain about the argument being unused. Once we do that, we can also combine the two cases into a single function definition and use if(IS_ENABLED()) rather than #ifdef to make it look a bit nicer. The warning first came up in linux-4.4, but I failed to catch it earlier. Signed-off-by: Arnd Bergmann Fixes: f86428854480 ("net: mvneta: Statically assign queues to CPUs") Signed-off-by: David S. Miller --- include/linux/netdevice.h | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-) diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index 5ac140dcb789..289c2314d766 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -512,7 +512,6 @@ static inline void napi_enable(struct napi_struct *n) clear_bit(NAPI_STATE_NPSVC, &n->state); } -#ifdef CONFIG_SMP /** * napi_synchronize - wait until NAPI is not running * @n: napi context @@ -523,12 +522,12 @@ static inline void napi_enable(struct napi_struct *n) */ static inline void napi_synchronize(const struct napi_struct *n) { - while (test_bit(NAPI_STATE_SCHED, &n->state)) - msleep(1); + if (IS_ENABLED(CONFIG_SMP)) + while (test_bit(NAPI_STATE_SCHED, &n->state)) + msleep(1); + else + barrier(); } -#else -# define napi_synchronize(n) barrier() -#endif enum netdev_queue_state_t { __QUEUE_STATE_DRV_XOFF, -- GitLab