Commit 29b8ea35 authored by Xin Long's avatar Xin Long Committed by Greg Kroah-Hartman

sctp: disable BH in sctp_for_each_endpoint


[ Upstream commit 581409da ]

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: 626d16f5 ("sctp: export some apis or variables for sctp_diag and reuse some for proc")
Reported-by: default avatarXiumei Mu <xmu@redhat.com>
Signed-off-by: default avatarXin Long <lucien.xin@gmail.com>
Acked-by: default avatarMarcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent e6077421
...@@ -4586,13 +4586,13 @@ int sctp_for_each_endpoint(int (*cb)(struct sctp_endpoint *, void *), ...@@ -4586,13 +4586,13 @@ int sctp_for_each_endpoint(int (*cb)(struct sctp_endpoint *, void *),
for (head = sctp_ep_hashtable; hash < sctp_ep_hashsize; for (head = sctp_ep_hashtable; hash < sctp_ep_hashsize;
hash++, head++) { hash++, head++) {
read_lock(&head->lock); read_lock_bh(&head->lock);
sctp_for_each_hentry(epb, &head->chain) { sctp_for_each_hentry(epb, &head->chain) {
err = cb(sctp_ep(epb), p); err = cb(sctp_ep(epb), p);
if (err) if (err)
break; break;
} }
read_unlock(&head->lock); read_unlock_bh(&head->lock);
} }
return err; return err;
......
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