* [PATCH] block: insert a general SMP memory barrier before wake_up_bit() @ 2020-08-13 2:44 Jacob Wen 2020-08-13 3:00 ` Chaitanya Kulkarni 2020-08-13 7:31 ` Christoph Hellwig 0 siblings, 2 replies; 6+ messages in thread From: Jacob Wen @ 2020-08-13 2:44 UTC (permalink / raw) To: linux-fsdevel wake_up_bit() uses waitqueue_active() that needs the explicit smp_mb(). Signed-off-by: Jacob Wen <jian.w.wen@oracle.com> --- fs/block_dev.c | 1 + 1 file changed, 1 insertion(+) diff --git a/fs/block_dev.c b/fs/block_dev.c index 0ae656e022fd..e74980848a2a 100644 --- a/fs/block_dev.c +++ b/fs/block_dev.c @@ -1175,6 +1175,7 @@ static void bd_clear_claiming(struct block_device *whole, void *holder) /* tell others that we're done */ BUG_ON(whole->bd_claiming != holder); whole->bd_claiming = NULL; + smp_mb(); wake_up_bit(&whole->bd_claiming, 0); } -- 2.17.1 ^ permalink raw reply related [flat|nested] 6+ messages in thread
* Re: [PATCH] block: insert a general SMP memory barrier before wake_up_bit() 2020-08-13 2:44 [PATCH] block: insert a general SMP memory barrier before wake_up_bit() Jacob Wen @ 2020-08-13 3:00 ` Chaitanya Kulkarni 2020-08-13 7:31 ` Christoph Hellwig 1 sibling, 0 replies; 6+ messages in thread From: Chaitanya Kulkarni @ 2020-08-13 3:00 UTC (permalink / raw) To: Jacob Wen, linux-fsdevel@vger.kernel.org On 8/12/20 19:46, Jacob Wen wrote: > wake_up_bit() uses waitqueue_active() that needs the explicit smp_mb(). > > Signed-off-by: Jacob Wen<jian.w.wen@oracle.com> As per wake_up_bit() documentation this looks good. Reviewed-by: Chaitanya Kulkarni<chaitanya.kulkarni@wdc.com> ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] block: insert a general SMP memory barrier before wake_up_bit() 2020-08-13 2:44 [PATCH] block: insert a general SMP memory barrier before wake_up_bit() Jacob Wen 2020-08-13 3:00 ` Chaitanya Kulkarni @ 2020-08-13 7:31 ` Christoph Hellwig 2020-08-13 7:46 ` Jacob Wen 2020-08-13 11:40 ` peterz 1 sibling, 2 replies; 6+ messages in thread From: Christoph Hellwig @ 2020-08-13 7:31 UTC (permalink / raw) To: Jacob Wen; +Cc: linux-fsdevel, linux-kernel, Peter Zijlstra On Thu, Aug 13, 2020 at 10:44:38AM +0800, Jacob Wen wrote: > wake_up_bit() uses waitqueue_active() that needs the explicit smp_mb(). Sounds like the barrier should go into wake_up_bit then.. > > Signed-off-by: Jacob Wen <jian.w.wen@oracle.com> > --- > fs/block_dev.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/fs/block_dev.c b/fs/block_dev.c > index 0ae656e022fd..e74980848a2a 100644 > --- a/fs/block_dev.c > +++ b/fs/block_dev.c > @@ -1175,6 +1175,7 @@ static void bd_clear_claiming(struct block_device *whole, void *holder) > /* tell others that we're done */ > BUG_ON(whole->bd_claiming != holder); > whole->bd_claiming = NULL; > + smp_mb(); > wake_up_bit(&whole->bd_claiming, 0); > } > > -- > 2.17.1 > ---end quoted text--- ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] block: insert a general SMP memory barrier before wake_up_bit() 2020-08-13 7:31 ` Christoph Hellwig @ 2020-08-13 7:46 ` Jacob Wen 2020-08-13 11:40 ` peterz 1 sibling, 0 replies; 6+ messages in thread From: Jacob Wen @ 2020-08-13 7:46 UTC (permalink / raw) To: Christoph Hellwig; +Cc: linux-fsdevel, linux-kernel, Peter Zijlstra On 8/13/20 3:31 PM, Christoph Hellwig wrote: > On Thu, Aug 13, 2020 at 10:44:38AM +0800, Jacob Wen wrote: >> wake_up_bit() uses waitqueue_active() that needs the explicit smp_mb(). > Sounds like the barrier should go into wake_up_bit then.. wake_up_bit() doesn't know which one to chose: smp_mb__after_atomic() or smp_mb(). > >> Signed-off-by: Jacob Wen <jian.w.wen@oracle.com> >> --- >> fs/block_dev.c | 1 + >> 1 file changed, 1 insertion(+) >> >> diff --git a/fs/block_dev.c b/fs/block_dev.c >> index 0ae656e022fd..e74980848a2a 100644 >> --- a/fs/block_dev.c >> +++ b/fs/block_dev.c >> @@ -1175,6 +1175,7 @@ static void bd_clear_claiming(struct block_device *whole, void *holder) >> /* tell others that we're done */ >> BUG_ON(whole->bd_claiming != holder); >> whole->bd_claiming = NULL; >> + smp_mb(); >> wake_up_bit(&whole->bd_claiming, 0); >> } >> >> -- >> 2.17.1 >> > ---end quoted text--- ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] block: insert a general SMP memory barrier before wake_up_bit() 2020-08-13 7:31 ` Christoph Hellwig 2020-08-13 7:46 ` Jacob Wen @ 2020-08-13 11:40 ` peterz 2020-08-13 12:00 ` Matthew Wilcox 1 sibling, 1 reply; 6+ messages in thread From: peterz @ 2020-08-13 11:40 UTC (permalink / raw) To: Christoph Hellwig; +Cc: Jacob Wen, linux-fsdevel, linux-kernel On Thu, Aug 13, 2020 at 08:31:15AM +0100, Christoph Hellwig wrote: > On Thu, Aug 13, 2020 at 10:44:38AM +0800, Jacob Wen wrote: > > wake_up_bit() uses waitqueue_active() that needs the explicit smp_mb(). > > Sounds like the barrier should go into wake_up_bit then.. Oh, thanks for reminding me.. https://lkml.kernel.org/r/20190624165012.GH3436@hirez.programming.kicks-ass.net I'll try and get back to that. ^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [PATCH] block: insert a general SMP memory barrier before wake_up_bit() 2020-08-13 11:40 ` peterz @ 2020-08-13 12:00 ` Matthew Wilcox 0 siblings, 0 replies; 6+ messages in thread From: Matthew Wilcox @ 2020-08-13 12:00 UTC (permalink / raw) To: peterz; +Cc: Christoph Hellwig, Jacob Wen, linux-fsdevel, linux-kernel On Thu, Aug 13, 2020 at 01:40:50PM +0200, peterz@infradead.org wrote: > On Thu, Aug 13, 2020 at 08:31:15AM +0100, Christoph Hellwig wrote: > > On Thu, Aug 13, 2020 at 10:44:38AM +0800, Jacob Wen wrote: > > > wake_up_bit() uses waitqueue_active() that needs the explicit smp_mb(). > > > > Sounds like the barrier should go into wake_up_bit then.. > > Oh, thanks for reminding me.. > > https://lkml.kernel.org/r/20190624165012.GH3436@hirez.programming.kicks-ass.net > > I'll try and get back to that. +++ b/drivers/bluetooth/btmtkuart.c @@ -340,11 +340,8 @@ static int btmtkuart_recv_event(struct hci_dev *hdev, struct sk_buff *skb) if (hdr->evt == HCI_EV_VENDOR) { if (test_and_clear_bit(BTMTKUART_TX_WAIT_VND_EVT, - &bdev->tx_state)) { - /* Barrier to sync with other CPUs */ - smp_mb__after_atomic(); + &bdev->tx_state)) wake_up_bit(&bdev->tx_state, BTMTKUART_TX_WAIT_VND_EVT); - } } return 0; It'd be nice to be able to write: if (hdr->evt == HCI_EV_VENDOR) test_clear_and_wake_up_bit(&bdev->tx_state, BTMTKUART_TX_WAIT_VND_EVT); ... maybe with a better name. ^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2020-08-13 12:02 UTC | newest] Thread overview: 6+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 2020-08-13 2:44 [PATCH] block: insert a general SMP memory barrier before wake_up_bit() Jacob Wen 2020-08-13 3:00 ` Chaitanya Kulkarni 2020-08-13 7:31 ` Christoph Hellwig 2020-08-13 7:46 ` Jacob Wen 2020-08-13 11:40 ` peterz 2020-08-13 12:00 ` Matthew Wilcox
This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox; as well as URLs for NNTP newsgroup(s).