| Message ID | 1412918694-22882-4-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| State | Superseded, archived |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> Change the title to :ixgbe: ...", then you have my ACK. 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/ixgbe/ixgbe_main.c | 8 +++----- > 1 file changed, 3 insertions(+), 5 deletions(-) > > diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c > index d677b5a23b58..fec5212d4337 100644 > --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c > +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c > @@ -1865,12 +1865,10 @@ static bool ixgbe_add_rx_frag(struct ixgbe_ring *rx_ring, > /* flip page offset to other buffer */ > rx_buffer->page_offset ^= truesize; > > - /* > - * 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 unecessary 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
diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c index d677b5a23b58..fec5212d4337 100644 --- a/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c +++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_main.c @@ -1865,12 +1865,10 @@ static bool ixgbe_add_rx_frag(struct ixgbe_ring *rx_ring, /* flip page offset to other buffer */ rx_buffer->page_offset ^= truesize; - /* - * 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 unecessary 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/ixgbe/ixgbe_main.c | 8 +++----- 1 file changed, 3 insertions(+), 5 deletions(-)