diff mbox series

[net-next,v8,2/3] net: tcp: un-pin the tw_timer

Message ID 20240606151332.21384-3-fw@strlen.de (mailing list archive)
State Accepted
Commit c75ad7c759ccead1be462d4cec42bd4ad3578989
Delegated to: Netdev Maintainers
Headers show
Series net: tcp: un-pin tw timer | expand

Checks

Context Check Description
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for net-next
netdev/ynl success Generated files up to date; no warnings/errors; no diff in generated;
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 903 this patch: 903
netdev/build_tools success No tools touched, skip
netdev/cc_maintainers warning 3 maintainers not CCed: kernelxing@tencent.com dsahern@kernel.org dccp@vger.kernel.org
netdev/build_clang success Errors and warnings before: 905 this patch: 905
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success No Fixes tag
netdev/build_allmodconfig_warn success Errors and warnings before: 907 this patch: 907
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 62 lines checked
netdev/build_clang_rust success No Rust files in patch. Skipping build
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0
netdev/contest success net-next-2024-06-07--09-00 (tests: 1041)

Commit Message

Florian Westphal June 6, 2024, 3:11 p.m. UTC 
After previous patch, even if timer fires immediately on another CPU,
context that schedules the timer now holds the ehash spinlock, so timer
cannot reap tw socket until ehash lock is released.

BH disable is moved into hashdance_schedule.

Signed-off-by: Florian Westphal <fw@strlen.de>
---
 Changes since last version:
 Move local_bh_enable/disable into inet_twsk_hashdance_schedule
 and remove the comments mentioning timer_pinned in the two callers.

 net/dccp/minisocks.c          | 6 ------
 net/ipv4/inet_timewait_sock.c | 6 ++++--
 net/ipv4/tcp_minisocks.c      | 6 ------
 3 files changed, 4 insertions(+), 14 deletions(-)

Comments

Eric Dumazet June 7, 2024, 5:51 a.m. UTC | #1 
On Thu, Jun 6, 2024 at 5:18 PM Florian Westphal <fw@strlen.de> wrote:
>
> After previous patch, even if timer fires immediately on another CPU,
> context that schedules the timer now holds the ehash spinlock, so timer
> cannot reap tw socket until ehash lock is released.
>
> BH disable is moved into hashdance_schedule.
>
> Signed-off-by: Florian Westphal <fw@strlen.de>
> ---
>

Reviewed-by: Eric Dumazet <edumazet@google.com>
diff mbox series

Patch

diff --git a/net/dccp/minisocks.c b/net/dccp/minisocks.c
index deb52d7d31b4..fecc8190064f 100644
--- a/net/dccp/minisocks.c
+++ b/net/dccp/minisocks.c
@@ -54,16 +54,10 @@  void dccp_time_wait(struct sock *sk, int state, int timeo)
 		if (state == DCCP_TIME_WAIT)
 			timeo = DCCP_TIMEWAIT_LEN;
 
-		/* tw_timer is pinned, so we need to make sure BH are disabled
-		 * in following section, otherwise timer handler could run before
-		 * we complete the initialization.
-		 */
-		local_bh_disable();
 		/* Linkage updates.
 		 * Note that access to tw after this point is illegal.
 		 */
 		inet_twsk_hashdance_schedule(tw, sk, &dccp_hashinfo, timeo);
-		local_bh_enable();
 	} else {
 		/* Sorry, if we're out of memory, just CLOSE this
 		 * socket up.  We've got bigger problems than
diff --git a/net/ipv4/inet_timewait_sock.c b/net/ipv4/inet_timewait_sock.c
index 628d33a41ce5..b2d97c816c99 100644
--- a/net/ipv4/inet_timewait_sock.c
+++ b/net/ipv4/inet_timewait_sock.c
@@ -93,7 +93,7 @@  static void inet_twsk_add_node_rcu(struct inet_timewait_sock *tw,
 }
 
 /*
- * Enter the time wait state. This is called with locally disabled BH.
+ * Enter the time wait state.
  * Essentially we whip up a timewait bucket, copy the relevant info into it
  * from the SK, and mess with hash chains and list linkage.
  *
@@ -118,6 +118,7 @@  void inet_twsk_hashdance_schedule(struct inet_timewait_sock *tw,
 			hashinfo->bhash_size)];
 	bhead2 = inet_bhashfn_portaddr(hashinfo, sk, twsk_net(tw), inet->inet_num);
 
+	local_bh_disable();
 	spin_lock(&bhead->lock);
 	spin_lock(&bhead2->lock);
 
@@ -158,6 +159,7 @@  void inet_twsk_hashdance_schedule(struct inet_timewait_sock *tw,
 	inet_twsk_schedule(tw, timeo);
 
 	spin_unlock(lock);
+	local_bh_enable();
 }
 EXPORT_SYMBOL_GPL(inet_twsk_hashdance_schedule);
 
@@ -203,7 +205,7 @@  struct inet_timewait_sock *inet_twsk_alloc(const struct sock *sk,
 		tw->tw_prot	    = sk->sk_prot_creator;
 		atomic64_set(&tw->tw_cookie, atomic64_read(&sk->sk_cookie));
 		twsk_net_set(tw, sock_net(sk));
-		timer_setup(&tw->tw_timer, tw_timer_handler, TIMER_PINNED);
+		timer_setup(&tw->tw_timer, tw_timer_handler, 0);
 		/*
 		 * Because we use RCU lookups, we should not set tw_refcnt
 		 * to a non null value before everything is setup for this
diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c
index fc9a850ed9bd..bc67f6b9efae 100644
--- a/net/ipv4/tcp_minisocks.c
+++ b/net/ipv4/tcp_minisocks.c
@@ -345,16 +345,10 @@  void tcp_time_wait(struct sock *sk, int state, int timeo)
 		if (state == TCP_TIME_WAIT)
 			timeo = TCP_TIMEWAIT_LEN;
 
-		/* tw_timer is pinned, so we need to make sure BH are disabled
-		 * in following section, otherwise timer handler could run before
-		 * we complete the initialization.
-		 */
-		local_bh_disable();
 		/* Linkage updates.
 		 * Note that access to tw after this point is illegal.
 		 */
 		inet_twsk_hashdance_schedule(tw, sk, net->ipv4.tcp_death_row.hashinfo, timeo);
-		local_bh_enable();
 	} else {
 		/* Sorry, if we're out of memory, just CLOSE this
 		 * socket up.  We've got bigger problems than