| Message ID | 20090608131143.10052.96470.stgit@localhost |
|---|---|
| State | Accepted, archived |
| Delegated to: | David Miller |
| Headers | show |
On Mon, Jun 08, 2009 at 03:11:43PM +0200, Jesper Dangaard Brouer wrote: > On module unload call rcu_barrier(), this is needed as synchronize_rcu() > is not strong enough. The kmem_cache_destroy() does invoke > synchronize_rcu() but it does not provide same protection. Good, looks like sctp_v4_del_protocol() invokes call_rcu(), which the rcu_barrier() would then wait for. And it looks like sctp_v6_del_protocol() does the same for IPv6. Reviewed_by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> > Signed-off-by: Jesper Dangaard Brouer <hawk@comx.dk> > --- > > net/sctp/protocol.c | 2 ++ > 1 files changed, 2 insertions(+), 0 deletions(-) > > diff --git a/net/sctp/protocol.c b/net/sctp/protocol.c > index cb2c50d..79cbd47 100644 > --- a/net/sctp/protocol.c > +++ b/net/sctp/protocol.c > @@ -1370,6 +1370,8 @@ SCTP_STATIC __exit void sctp_exit(void) > sctp_proc_exit(); > cleanup_sctp_mibs(); > > + rcu_barrier(); /* Wait for completion of call_rcu()'s */ > + > kmem_cache_destroy(sctp_chunk_cachep); > kmem_cache_destroy(sctp_bucket_cachep); > } > -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Paul E. McKenney wrote: > On Mon, Jun 08, 2009 at 03:11:43PM +0200, Jesper Dangaard Brouer wrote: >> On module unload call rcu_barrier(), this is needed as synchronize_rcu() >> is not strong enough. The kmem_cache_destroy() does invoke >> synchronize_rcu() but it does not provide same protection. > > Good, looks like sctp_v4_del_protocol() invokes call_rcu(), which the > rcu_barrier() would then wait for. And it looks like sctp_v6_del_protocol() > does the same for IPv6. > > Reviewed_by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> > >> Signed-off-by: Jesper Dangaard Brouer <hawk@comx.dk> >> --- >> >> net/sctp/protocol.c | 2 ++ >> 1 files changed, 2 insertions(+), 0 deletions(-) >> >> diff --git a/net/sctp/protocol.c b/net/sctp/protocol.c >> index cb2c50d..79cbd47 100644 >> --- a/net/sctp/protocol.c >> +++ b/net/sctp/protocol.c >> @@ -1370,6 +1370,8 @@ SCTP_STATIC __exit void sctp_exit(void) >> sctp_proc_exit(); >> cleanup_sctp_mibs(); >> >> + rcu_barrier(); /* Wait for completion of call_rcu()'s */ >> + >> kmem_cache_destroy(sctp_chunk_cachep); >> kmem_cache_destroy(sctp_bucket_cachep); >> } >> Shouldn't the rcu_barrier call be before sctp_free_local_addr_list()? -vlad -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue, Jun 09, 2009 at 11:44:23AM -0400, Vlad Yasevich wrote: > Paul E. McKenney wrote: > > On Mon, Jun 08, 2009 at 03:11:43PM +0200, Jesper Dangaard Brouer wrote: > >> On module unload call rcu_barrier(), this is needed as synchronize_rcu() > >> is not strong enough. The kmem_cache_destroy() does invoke > >> synchronize_rcu() but it does not provide same protection. > > > > Good, looks like sctp_v4_del_protocol() invokes call_rcu(), which the > > rcu_barrier() would then wait for. And it looks like sctp_v6_del_protocol() > > does the same for IPv6. > > > > Reviewed_by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> > > > >> Signed-off-by: Jesper Dangaard Brouer <hawk@comx.dk> > >> --- > >> > >> net/sctp/protocol.c | 2 ++ > >> 1 files changed, 2 insertions(+), 0 deletions(-) > >> > >> diff --git a/net/sctp/protocol.c b/net/sctp/protocol.c > >> index cb2c50d..79cbd47 100644 > >> --- a/net/sctp/protocol.c > >> +++ b/net/sctp/protocol.c > >> @@ -1370,6 +1370,8 @@ SCTP_STATIC __exit void sctp_exit(void) > >> sctp_proc_exit(); > >> cleanup_sctp_mibs(); > >> > >> + rcu_barrier(); /* Wait for completion of call_rcu()'s */ > >> + > >> kmem_cache_destroy(sctp_chunk_cachep); > >> kmem_cache_destroy(sctp_bucket_cachep); > >> } > > Shouldn't the rcu_barrier call be before sctp_free_local_addr_list()? Hmmm... What sequence of events would lead to a failure if rcu_barrier() is after sctp_free_local_addr_list()? Thanx, Paul -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Paul E. McKenney wrote: > On Tue, Jun 09, 2009 at 11:44:23AM -0400, Vlad Yasevich wrote: >> Paul E. McKenney wrote: >>> On Mon, Jun 08, 2009 at 03:11:43PM +0200, Jesper Dangaard Brouer wrote: >>>> On module unload call rcu_barrier(), this is needed as synchronize_rcu() >>>> is not strong enough. The kmem_cache_destroy() does invoke >>>> synchronize_rcu() but it does not provide same protection. >>> Good, looks like sctp_v4_del_protocol() invokes call_rcu(), which the >>> rcu_barrier() would then wait for. And it looks like sctp_v6_del_protocol() >>> does the same for IPv6. >>> >>> Reviewed_by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> >>> >>>> Signed-off-by: Jesper Dangaard Brouer <hawk@comx.dk> >>>> --- >>>> >>>> net/sctp/protocol.c | 2 ++ >>>> 1 files changed, 2 insertions(+), 0 deletions(-) >>>> >>>> diff --git a/net/sctp/protocol.c b/net/sctp/protocol.c >>>> index cb2c50d..79cbd47 100644 >>>> --- a/net/sctp/protocol.c >>>> +++ b/net/sctp/protocol.c >>>> @@ -1370,6 +1370,8 @@ SCTP_STATIC __exit void sctp_exit(void) >>>> sctp_proc_exit(); >>>> cleanup_sctp_mibs(); >>>> >>>> + rcu_barrier(); /* Wait for completion of call_rcu()'s */ >>>> + >>>> kmem_cache_destroy(sctp_chunk_cachep); >>>> kmem_cache_destroy(sctp_bucket_cachep); >>>> } >> Shouldn't the rcu_barrier call be before sctp_free_local_addr_list()? > > Hmmm... What sequence of events would lead to a failure if > rcu_barrier() is after sctp_free_local_addr_list()? > > Thanx, Paul > I thought that the notifier could could potentially execute at the same time as the unregister(), but I see that's protected. So, I guess it doesn't really matter then where the barrier is. Acked-by: Vlad Yasevich <vladislav.yasevich@hp.com> -vlad -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/net/sctp/protocol.c b/net/sctp/protocol.c index cb2c50d..79cbd47 100644 --- a/net/sctp/protocol.c +++ b/net/sctp/protocol.c @@ -1370,6 +1370,8 @@ SCTP_STATIC __exit void sctp_exit(void) sctp_proc_exit(); cleanup_sctp_mibs(); + rcu_barrier(); /* Wait for completion of call_rcu()'s */ + kmem_cache_destroy(sctp_chunk_cachep); kmem_cache_destroy(sctp_bucket_cachep); }
On module unload call rcu_barrier(), this is needed as synchronize_rcu() is not strong enough. The kmem_cache_destroy() does invoke synchronize_rcu() but it does not provide same protection. Signed-off-by: Jesper Dangaard Brouer <hawk@comx.dk> --- net/sctp/protocol.c | 2 ++ 1 files changed, 2 insertions(+), 0 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html