Merge branch 'net-try_cmpxchg-conversions'

Eric Dumazet says:

====================
net: more try_cmpxchg() conversions

Adopt try_cmpxchg() and friends in more places, as this
is preferred nowadays.
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/core/dev.c

@@ -2073,13 +2073,10 @@ static DECLARE_WORK(netstamp_work, netstamp_clear);
 void net_enable_timestamp(void)
 {
 #ifdef CONFIG_JUMP_LABEL
-	int wanted;
+	int wanted = atomic_read(&netstamp_wanted);
 
-	while (1) {
-		wanted = atomic_read(&netstamp_wanted);
-		if (wanted <= 0)
-			break;
-		if (atomic_cmpxchg(&netstamp_wanted, wanted, wanted + 1) == wanted)
+	while (wanted > 0) {
+		if (atomic_try_cmpxchg(&netstamp_wanted, &wanted, wanted + 1))
 			return;
 	}
 	atomic_inc(&netstamp_needed_deferred);
@@ -2093,13 +2090,10 @@ EXPORT_SYMBOL(net_enable_timestamp);
 void net_disable_timestamp(void)
 {
 #ifdef CONFIG_JUMP_LABEL
-	int wanted;
+	int wanted = atomic_read(&netstamp_wanted);
 
-	while (1) {
-		wanted = atomic_read(&netstamp_wanted);
-		if (wanted <= 1)
-			break;
-		if (atomic_cmpxchg(&netstamp_wanted, wanted, wanted - 1) == wanted)
+	while (wanted > 1) {
+		if (atomic_try_cmpxchg(&netstamp_wanted, &wanted, wanted - 1))
 			return;
 	}
 	atomic_dec(&netstamp_needed_deferred);
@@ -5985,10 +5979,9 @@ EXPORT_SYMBOL(__napi_schedule);
  */
 bool napi_schedule_prep(struct napi_struct *n)
 {
-	unsigned long val, new;
+	unsigned long new, val = READ_ONCE(n->state);
 
 	do {
-		val = READ_ONCE(n->state);
 		if (unlikely(val & NAPIF_STATE_DISABLE))
 			return false;
 		new = val | NAPIF_STATE_SCHED;
@@ -6001,7 +5994,7 @@ bool napi_schedule_prep(struct napi_struct *n)
 		 */
 		new |= (val & NAPIF_STATE_SCHED) / NAPIF_STATE_SCHED *
 						   NAPIF_STATE_MISSED;
-	} while (cmpxchg(&n->state, val, new) != val);
+	} while (!try_cmpxchg(&n->state, &val, new));
 
 	return !(val & NAPIF_STATE_SCHED);
 }
@@ -6069,9 +6062,8 @@ bool napi_complete_done(struct napi_struct *n, int work_done)
 		local_irq_restore(flags);
 	}
 
+	val = READ_ONCE(n->state);
 	do {
-		val = READ_ONCE(n->state);
-
 		WARN_ON_ONCE(!(val & NAPIF_STATE_SCHED));
 
 		new = val & ~(NAPIF_STATE_MISSED | NAPIF_STATE_SCHED |
@@ -6084,7 +6076,7 @@ bool napi_complete_done(struct napi_struct *n, int work_done)
 		 */
 		new |= (val & NAPIF_STATE_MISSED) / NAPIF_STATE_MISSED *
 						    NAPIF_STATE_SCHED;
-	} while (cmpxchg(&n->state, val, new) != val);
+	} while (!try_cmpxchg(&n->state, &val, new));
 
 	if (unlikely(val & NAPIF_STATE_MISSED)) {
 		__napi_schedule(n);
@@ -6405,8 +6397,8 @@ void napi_disable(struct napi_struct *n)
 	might_sleep();
 	set_bit(NAPI_STATE_DISABLE, &n->state);
 
-	for ( ; ; ) {
-		val = READ_ONCE(n->state);
+	val = READ_ONCE(n->state);
+	do {
 		if (val & (NAPIF_STATE_SCHED | NAPIF_STATE_NPSVC)) {
 			usleep_range(20, 200);
 			continue;
@@ -6414,10 +6406,7 @@ void napi_disable(struct napi_struct *n)
 
 		new = val | NAPIF_STATE_SCHED | NAPIF_STATE_NPSVC;
 		new &= ~(NAPIF_STATE_THREADED | NAPIF_STATE_PREFER_BUSY_POLL);
-
-		if (cmpxchg(&n->state, val, new) == val)
-			break;
-	}
+	} while (!try_cmpxchg(&n->state, &val, new));
 
 	hrtimer_cancel(&n->timer);
 
@@ -6434,16 +6423,15 @@ EXPORT_SYMBOL(napi_disable);
  */
 void napi_enable(struct napi_struct *n)
 {
-	unsigned long val, new;
+	unsigned long new, val = READ_ONCE(n->state);
 
 	do {
-		val = READ_ONCE(n->state);
 		BUG_ON(!test_bit(NAPI_STATE_SCHED, &val));
 
 		new = val & ~(NAPIF_STATE_SCHED | NAPIF_STATE_NPSVC);
 		if (n->dev->threaded && n->thread)
 			new |= NAPIF_STATE_THREADED;
-	} while (cmpxchg(&n->state, val, new) != val);
+	} while (!try_cmpxchg(&n->state, &val, new));
 }
 EXPORT_SYMBOL(napi_enable);
 

net/core/skbuff.c

@@ -1267,13 +1267,12 @@ int mm_account_pinned_pages(struct mmpin *mmp, size_t size)
 	max_pg = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
 	user = mmp->user ? : current_user();
 
+	old_pg = atomic_long_read(&user->locked_vm);
 	do {
-		old_pg = atomic_long_read(&user->locked_vm);
 		new_pg = old_pg + num_pg;
 		if (new_pg > max_pg)
 			return -ENOBUFS;
-	} while (atomic_long_cmpxchg(&user->locked_vm, old_pg, new_pg) !=
-		 old_pg);
+	} while (!atomic_long_try_cmpxchg(&user->locked_vm, &old_pg, new_pg));
 
 	if (!mmp->user) {
 		mmp->user = get_uid(user);

net/core/sock_diag.c

@@ -25,14 +25,14 @@ DEFINE_COOKIE(sock_cookie);
 
 u64 __sock_gen_cookie(struct sock *sk)
 {
-	while (1) {
-		u64 res = atomic64_read(&sk->sk_cookie);
+	u64 res = atomic64_read(&sk->sk_cookie);
 
-		if (res)
-			return res;
-		res = gen_cookie_next(&sock_cookie);
-		atomic64_cmpxchg(&sk->sk_cookie, 0, res);
+	if (!res) {
+		u64 new = gen_cookie_next(&sock_cookie);
+
+		atomic64_try_cmpxchg(&sk->sk_cookie, &res, new);
 	}
+	return res;
 }
 
 int sock_diag_check_cookie(struct sock *sk, const __u32 *cookie)

net/ipv6/ip6_fib.c

@@ -91,13 +91,12 @@ static void fib6_walker_unlink(struct net *net, struct fib6_walker *w)
 
 static int fib6_new_sernum(struct net *net)
 {
-	int new, old;
+	int new, old = atomic_read(&net->ipv6.fib6_sernum);
 
 	do {
-		old = atomic_read(&net->ipv6.fib6_sernum);
 		new = old < INT_MAX ? old + 1 : 1;
-	} while (atomic_cmpxchg(&net->ipv6.fib6_sernum,
-				old, new) != old);
+	} while (!atomic_try_cmpxchg(&net->ipv6.fib6_sernum, &old, new));
+
 	return new;
 }