| Message ID | fc2c69db46c2dc7c877a54fc0b0917d99d0b7f0c.1497077294.git.lucien.xin@gmail.com |
|---|---|
| State | Accepted, archived |
| Delegated to: | David Miller |
| Headers | show |
On Sat, Jun 10, 2017 at 02:48:14PM +0800, Xin Long wrote: > Now sctp holds read_lock when foreach sctp_ep_hashtable without disabling > BH. If CPU schedules to another thread A at this moment, the thread A may > be trying to hold the write_lock with disabling BH. > > As BH is disabled and CPU cannot schedule back to the thread holding the > read_lock, while the thread A keeps waiting for the read_lock. A dead > lock would be triggered by this. > > This patch is to fix this dead lock by calling read_lock_bh instead to > disable BH when holding the read_lock in sctp_for_each_endpoint. > > Fixes: 626d16f50f39 ("sctp: export some apis or variables for sctp_diag and reuse some for proc") > Reported-by: Xiumei Mu <xmu@redhat.com> > Signed-off-by: Xin Long <lucien.xin@gmail.com> Similar is done for proc interface already (sctp_eps_seq_show). Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com> > --- > net/sctp/socket.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/net/sctp/socket.c b/net/sctp/socket.c > index f16c8d9..30aa0a5 100644 > --- a/net/sctp/socket.c > +++ b/net/sctp/socket.c > @@ -4622,13 +4622,13 @@ int sctp_for_each_endpoint(int (*cb)(struct sctp_endpoint *, void *), > > for (head = sctp_ep_hashtable; hash < sctp_ep_hashsize; > hash++, head++) { > - read_lock(&head->lock); > + read_lock_bh(&head->lock); > sctp_for_each_hentry(epb, &head->chain) { > err = cb(sctp_ep(epb), p); > if (err) > break; > } > - read_unlock(&head->lock); > + read_unlock_bh(&head->lock); > } > > return err; > -- > 2.1.0 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-sctp" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >
From: Xin Long <lucien.xin@gmail.com> Date: Sat, 10 Jun 2017 14:48:14 +0800 > Now sctp holds read_lock when foreach sctp_ep_hashtable without disabling > BH. If CPU schedules to another thread A at this moment, the thread A may > be trying to hold the write_lock with disabling BH. > > As BH is disabled and CPU cannot schedule back to the thread holding the > read_lock, while the thread A keeps waiting for the read_lock. A dead > lock would be triggered by this. > > This patch is to fix this dead lock by calling read_lock_bh instead to > disable BH when holding the read_lock in sctp_for_each_endpoint. > > Fixes: 626d16f50f39 ("sctp: export some apis or variables for sctp_diag and reuse some for proc") > Reported-by: Xiumei Mu <xmu@redhat.com> > Signed-off-by: Xin Long <lucien.xin@gmail.com> Applied and queued up for -stable, thanks.
diff --git a/net/sctp/socket.c b/net/sctp/socket.c index f16c8d9..30aa0a5 100644 --- a/net/sctp/socket.c +++ b/net/sctp/socket.c @@ -4622,13 +4622,13 @@ int sctp_for_each_endpoint(int (*cb)(struct sctp_endpoint *, void *), for (head = sctp_ep_hashtable; hash < sctp_ep_hashsize; hash++, head++) { - read_lock(&head->lock); + read_lock_bh(&head->lock); sctp_for_each_hentry(epb, &head->chain) { err = cb(sctp_ep(epb), p); if (err) break; } - read_unlock(&head->lock); + read_unlock_bh(&head->lock); } return err;
Now sctp holds read_lock when foreach sctp_ep_hashtable without disabling BH. If CPU schedules to another thread A at this moment, the thread A may be trying to hold the write_lock with disabling BH. As BH is disabled and CPU cannot schedule back to the thread holding the read_lock, while the thread A keeps waiting for the read_lock. A dead lock would be triggered by this. This patch is to fix this dead lock by calling read_lock_bh instead to disable BH when holding the read_lock in sctp_for_each_endpoint. Fixes: 626d16f50f39 ("sctp: export some apis or variables for sctp_diag and reuse some for proc") Reported-by: Xiumei Mu <xmu@redhat.com> Signed-off-by: Xin Long <lucien.xin@gmail.com> --- net/sctp/socket.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)