| Message ID | 1412918694-22882-3-git-send-email-edumazet@google.com |
|---|---|
| State | Superseded, archived |
| Delegated to: | David Miller |
| Headers | show |
On Thu, Oct 9, 2014 at 10:24 PM, Eric Dumazet <edumazet@google.com> wrote: > This is illegal to use atomic_set(&page->_count, 2) even if we 'own' > the page. Other entities in the kernel need to use get_page_unless_zero() > to get a reference to the page before testing page properties, so we could > loose a refcount increment. > > Signed-off-by: Eric Dumazet <edumazet@google.com> Acked-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com> Since this is apart of a series, if the changes to skbuff are ok, then the changes to the Intel drivers are ok. > --- > drivers/net/ethernet/intel/igb/igb_main.c | 7 +++---- > 1 file changed, 3 insertions(+), 4 deletions(-) > > diff --git a/drivers/net/ethernet/intel/igb/igb_main.c b/drivers/net/ethernet/intel/igb/igb_main.c > index ae59c0b108c5..a21b14495ebd 100644 > --- a/drivers/net/ethernet/intel/igb/igb_main.c > +++ b/drivers/net/ethernet/intel/igb/igb_main.c > @@ -6545,11 +6545,10 @@ static bool igb_can_reuse_rx_page(struct igb_rx_buffer *rx_buffer, > /* flip page offset to other buffer */ > rx_buffer->page_offset ^= IGB_RX_BUFSZ; > > - /* since we are the only owner of the page and we need to > - * increment it, just set the value to 2 in order to avoid > - * an unnecessary locked operation > + /* Even if we own the page, we are not allowed to use atomic_set() > + * This would break get_page_unless_zero() users. > */ > - atomic_set(&page->_count, 2); > + atomic_inc(&page->_count); > #else > /* move offset up to the next cache line */ > rx_buffer->page_offset += truesize; > -- > 2.1.0.rc2.206.gedb03e5 > > -- > To unsubscribe from this list: send the line "unsubscribe netdev" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thu, 2014-10-09 at 22:55 -0700, Jeff Kirsher wrote: > On Thu, Oct 9, 2014 at 10:24 PM, Eric Dumazet <edumazet@google.com> wrote: > > This is illegal to use atomic_set(&page->_count, 2) even if we 'own' > > the page. Other entities in the kernel need to use get_page_unless_zero() > > to get a reference to the page before testing page properties, so we could > > loose a refcount increment. > > > > Signed-off-by: Eric Dumazet <edumazet@google.com> > > Acked-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com> > > Since this is apart of a series, if the changes to skbuff are ok, then > the changes to the Intel drivers are ok. Thanks Jeff, I am sending v2 including your Acked-by and ixgbe title fix. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/net/ethernet/intel/igb/igb_main.c b/drivers/net/ethernet/intel/igb/igb_main.c index ae59c0b108c5..a21b14495ebd 100644 --- a/drivers/net/ethernet/intel/igb/igb_main.c +++ b/drivers/net/ethernet/intel/igb/igb_main.c @@ -6545,11 +6545,10 @@ static bool igb_can_reuse_rx_page(struct igb_rx_buffer *rx_buffer, /* flip page offset to other buffer */ rx_buffer->page_offset ^= IGB_RX_BUFSZ; - /* since we are the only owner of the page and we need to - * increment it, just set the value to 2 in order to avoid - * an unnecessary locked operation + /* Even if we own the page, we are not allowed to use atomic_set() + * This would break get_page_unless_zero() users. */ - atomic_set(&page->_count, 2); + atomic_inc(&page->_count); #else /* move offset up to the next cache line */ rx_buffer->page_offset += truesize;
This is illegal to use atomic_set(&page->_count, 2) even if we 'own' the page. Other entities in the kernel need to use get_page_unless_zero() to get a reference to the page before testing page properties, so we could loose a refcount increment. Signed-off-by: Eric Dumazet <edumazet@google.com> --- drivers/net/ethernet/intel/igb/igb_main.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-)