On Mon, Feb 10, 2014 at 12:54:59PM -0800, Nicholas A. Bellinger wrote: > Hi Greg, > > On Mon, 2014-02-10 at 11:44 -0800, [email protected] wrote: > > The patch below does not apply to the 3.13-stable tree. > > If someone wants it applied there, or to any other stable or longterm > > tree, then please email the backport, including the original git commit > > id to <[email protected]>. > > > > thanks, > > > > greg k-h > > > > > > ------------------ original commit in Linus's tree ------------------ > > > > From 5259a06ef97068b710f45d092a587e8d740f750f Mon Sep 17 00:00:00 2001 > > From: Nicholas Bellinger <[email protected]> > > Date: Tue, 28 Jan 2014 17:56:30 -0800 > > Subject: [PATCH] target: Fix percpu_ref_put race in transport_lun_remove_cmd > > > > This patch fixes a percpu_ref_put race for se_lun->lun_ref in > > transport_lun_remove_cmd() where ->lun_ref could end up being > > put more than once per command via different target completion > > and fabric release contexts. > > > > It adds a cmpxchg() for se_cmd->lun_ref_active to ensure that > > percpu_ref_put() is only ever called once per se_cmd. > > > > This bug was manifesting itself as a LUN shutdown regression > > bug in >= v3.13 code, where percpu_ref_kill() would end up > > hanging indefinately due to the incorrect percpu_ref count. > > > > (Change se_cmd->lun_ref_active from bool -> int to force at > > least a 4-byte cmpxchg with MIPS ll/sc ins. - Fengguang) > > > > Reported-by: Tommy Apel <[email protected]> > > Cc: Tommy Apel <[email protected]> > > Cc: <[email protected]> #3.13+ > > Signed-off-by: Nicholas Bellinger <[email protected]> > > > > diff --git a/drivers/target/target_core_transport.c > > b/drivers/target/target_core_transport.c > > index 51a9736be726..c50fd9f11aab 100644 > > --- a/drivers/target/target_core_transport.c > > +++ b/drivers/target/target_core_transport.c > > @@ -594,10 +594,11 @@ static void transport_lun_remove_cmd(struct se_cmd > > *cmd) > > { > > struct se_lun *lun = cmd->se_lun; > > > > - if (!lun || !cmd->lun_ref_active) > > + if (!lun) > > return; > > > > - percpu_ref_put(&lun->lun_ref); > > + if (cmpxchg(&cmd->lun_ref_active, true, false)) > > + percpu_ref_put(&lun->lun_ref); > > } > > > > void transport_cmd_finish_abort(struct se_cmd *cmd, int remove) > > diff --git a/include/target/target_core_base.h > > b/include/target/target_core_base.h > > index d28418645b00..909dacbd230f 100644 > > --- a/include/target/target_core_base.h > > +++ b/include/target/target_core_base.h > > @@ -552,7 +552,7 @@ struct se_cmd { > > void *priv; > > > > /* Used for lun->lun_ref counting */ > > - bool lun_ref_active; > > + int lun_ref_active; > > > > /* DIF related members */ > > enum target_prot_op prot_op; > > > > > There is a small context change in target_core_base.h on this one.. > > Please apply for v3.13.y code. > > Thank you, > > --nab > > diff --git a/drivers/target/target_core_transport.c > b/drivers/target/target_core_transport.c > index 91953da..dee2be1 100644 > --- a/drivers/target/target_core_transport.c > +++ b/drivers/target/target_core_transport.c > @@ -568,10 +568,11 @@ static void transport_lun_remove_cmd(struct se_cmd *cmd) > { > struct se_lun *lun = cmd->se_lun; > > - if (!lun || !cmd->lun_ref_active) > + if (!lun) > return;
This patch is corrupted and can't be applied at all, please fix your email client to not convert tabs to spaces :( Care to try it again? thanks, greg k-h -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
