Message ID | 1459474756.6473.248.camel@edumazet-glaptop3.roam.corp.google.com |
---|---|
State | RFC, archived |
Delegated to: | David Miller |
Headers | show |
On Thu, 2016-03-31 at 18:39 -0700, Eric Dumazet wrote: > On Fri, 2016-04-01 at 03:36 +0200, Hannes Frederic Sowa wrote: > > On Fri, Apr 1, 2016, at 03:19, Eric Dumazet wrote: > > > Thanks. > > > > > > As you can see, release_sock() messes badly lockdep (once your other > > > patches are in ) > > > > > > Once we properly fix release_sock() and/or __release_sock(), all these > > > false positives disappear. > > > > This was a loopback connection. I need to study release_sock and > > __release_sock more as I cannot currently see an issue with the lockdep > > handling. > > Okay, please try : > > diff --git a/net/core/sock.c b/net/core/sock.c > index b67b9aedb230..570dcd91d64e 100644 > --- a/net/core/sock.c > +++ b/net/core/sock.c > @@ -2429,10 +2429,6 @@ EXPORT_SYMBOL(lock_sock_nested); > > void release_sock(struct sock *sk) > { > - /* > - * The sk_lock has mutex_unlock() semantics: > - */ > - mutex_release(&sk->sk_lock.dep_map, 1, _RET_IP_); > > spin_lock_bh(&sk->sk_lock.slock); > if (sk->sk_backlog.tail) > @@ -2445,6 +2441,10 @@ void release_sock(struct sock *sk) > sk->sk_prot->release_cb(sk); > > sock_release_ownership(sk); > + /* > + * The sk_lock has mutex_unlock() semantics: > + */ > + mutex_release(&sk->sk_lock.dep_map, 1, _RET_IP_); > if (waitqueue_active(&sk->sk_lock.wq)) > wake_up(&sk->sk_lock.wq); > spin_unlock_bh(&sk->sk_lock.slock); Also take a look at commit c3f9b01849ef3bc69024990092b9f42e20df7797 We might need to include the mutex_release() in sock_release_ownership() Thanks !
On 01.04.2016 03:39, Eric Dumazet wrote: > On Fri, 2016-04-01 at 03:36 +0200, Hannes Frederic Sowa wrote: >> On Fri, Apr 1, 2016, at 03:19, Eric Dumazet wrote: >>> Thanks. >>> >>> As you can see, release_sock() messes badly lockdep (once your other >>> patches are in ) >>> >>> Once we properly fix release_sock() and/or __release_sock(), all these >>> false positives disappear. >> >> This was a loopback connection. I need to study release_sock and >> __release_sock more as I cannot currently see an issue with the lockdep >> handling. > > Okay, please try : > > diff --git a/net/core/sock.c b/net/core/sock.c > index b67b9aedb230..570dcd91d64e 100644 > --- a/net/core/sock.c > +++ b/net/core/sock.c > @@ -2429,10 +2429,6 @@ EXPORT_SYMBOL(lock_sock_nested); > > void release_sock(struct sock *sk) > { > - /* > - * The sk_lock has mutex_unlock() semantics: > - */ > - mutex_release(&sk->sk_lock.dep_map, 1, _RET_IP_); > > spin_lock_bh(&sk->sk_lock.slock); > if (sk->sk_backlog.tail) > @@ -2445,6 +2441,10 @@ void release_sock(struct sock *sk) > sk->sk_prot->release_cb(sk); > > sock_release_ownership(sk); > + /* > + * The sk_lock has mutex_unlock() semantics: > + */ > + mutex_release(&sk->sk_lock.dep_map, 1, _RET_IP_); > if (waitqueue_active(&sk->sk_lock.wq)) > wake_up(&sk->sk_lock.wq); > spin_unlock_bh(&sk->sk_lock.slock); Looks much better with your patch already. I slowly begin to understand, this is really tricky... :) Bye, Hannes
On 01.04.2016 03:45, Eric Dumazet wrote: > On Thu, 2016-03-31 at 18:39 -0700, Eric Dumazet wrote: >> On Fri, 2016-04-01 at 03:36 +0200, Hannes Frederic Sowa wrote: >>> On Fri, Apr 1, 2016, at 03:19, Eric Dumazet wrote: >>>> Thanks. >>>> >>>> As you can see, release_sock() messes badly lockdep (once your other >>>> patches are in ) >>>> >>>> Once we properly fix release_sock() and/or __release_sock(), all these >>>> false positives disappear. >>> >>> This was a loopback connection. I need to study release_sock and >>> __release_sock more as I cannot currently see an issue with the lockdep >>> handling. >> >> Okay, please try : >> >> diff --git a/net/core/sock.c b/net/core/sock.c >> index b67b9aedb230..570dcd91d64e 100644 >> --- a/net/core/sock.c >> +++ b/net/core/sock.c >> @@ -2429,10 +2429,6 @@ EXPORT_SYMBOL(lock_sock_nested); >> >> void release_sock(struct sock *sk) >> { >> - /* >> - * The sk_lock has mutex_unlock() semantics: >> - */ >> - mutex_release(&sk->sk_lock.dep_map, 1, _RET_IP_); >> >> spin_lock_bh(&sk->sk_lock.slock); >> if (sk->sk_backlog.tail) >> @@ -2445,6 +2441,10 @@ void release_sock(struct sock *sk) >> sk->sk_prot->release_cb(sk); >> >> sock_release_ownership(sk); >> + /* >> + * The sk_lock has mutex_unlock() semantics: >> + */ >> + mutex_release(&sk->sk_lock.dep_map, 1, _RET_IP_); >> if (waitqueue_active(&sk->sk_lock.wq)) >> wake_up(&sk->sk_lock.wq); >> spin_unlock_bh(&sk->sk_lock.slock); > > Also take a look at commit c3f9b01849ef3bc69024990092b9f42e20df7797 > > We might need to include the mutex_release() in sock_release_ownership() I thought so first, as well. But given the double check for the spin_lock and the "mutex" we end up with the same result for the lockdep_sock_is_held check. Do you see other consequences? Thanks, Hannes
diff --git a/net/core/sock.c b/net/core/sock.c index b67b9aedb230..570dcd91d64e 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -2429,10 +2429,6 @@ EXPORT_SYMBOL(lock_sock_nested); void release_sock(struct sock *sk) { - /* - * The sk_lock has mutex_unlock() semantics: - */ - mutex_release(&sk->sk_lock.dep_map, 1, _RET_IP_); spin_lock_bh(&sk->sk_lock.slock); if (sk->sk_backlog.tail) @@ -2445,6 +2441,10 @@ void release_sock(struct sock *sk) sk->sk_prot->release_cb(sk); sock_release_ownership(sk); + /* + * The sk_lock has mutex_unlock() semantics: + */ + mutex_release(&sk->sk_lock.dep_map, 1, _RET_IP_); if (waitqueue_active(&sk->sk_lock.wq)) wake_up(&sk->sk_lock.wq); spin_unlock_bh(&sk->sk_lock.slock);