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Date: Mon, 18 Mar 2013 18:53:54 -0700 From: Greg Kroah-Hartman <gregkh@...uxfoundation.org> To: Jörn Engel <joern@...fs.org> Cc: "Nicholas A. Bellinger" <nab@...ux-iscsi.org>, linux-kernel@...r.kernel.org, target-devel <target-devel@...r.kernel.org> Subject: Re: [PATCH v3] target: close target_put_sess_cmd() vs. core_tmr_abort_task() race On Mon, Mar 18, 2013 at 07:34:13PM -0400, Jörn Engel wrote: > And because I'm lame and stupid, here's v3. > > It is possible for one thread to to take se_sess->sess_cmd_lock in > core_tmr_abort_task() before taking a reference count on > se_cmd->cmd_kref, while another thread in target_put_sess_cmd() drops > se_cmd->cmd_kref before taking se_sess->sess_cmd_lock. > > This introduces kref_put_and_lock() and uses it in > target_put_sess_cmd() to close the race window. > > Signed-off-by: Joern Engel <joern@...fs.org> > --- > drivers/target/target_core_transport.c | 17 +++++++++++------ > include/linux/kref.h | 26 ++++++++++++++++++++++++++ > 2 files changed, 37 insertions(+), 6 deletions(-) > > diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c > index 04ec9cb..b98c158 100644 > --- a/drivers/target/target_core_transport.c > +++ b/drivers/target/target_core_transport.c > @@ -2207,21 +2207,19 @@ static void target_release_cmd_kref(struct kref *kref) > { > struct se_cmd *se_cmd = container_of(kref, struct se_cmd, cmd_kref); > struct se_session *se_sess = se_cmd->se_sess; > - unsigned long flags; > > - spin_lock_irqsave(&se_sess->sess_cmd_lock, flags); > if (list_empty(&se_cmd->se_cmd_list)) { > - spin_unlock_irqrestore(&se_sess->sess_cmd_lock, flags); > + spin_unlock(&se_sess->sess_cmd_lock); Wait, who has this locked? You took out the call to spin_lock_* above. And why not _irqstore() anymore? thanks, greg k-h -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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