| Message ID | 20241204114229.21452-2-wander@redhat.com |
|---|---|
| State | Under Review |
| Delegated to: | Anthony Nguyen |
| Headers | show |
| Series | igb: fix igb_msix_other() handling for PREEMPT_RT | expand |
> -----Original Message----- > From: Intel-wired-lan <intel-wired-lan-bounces@osuosl.org> On Behalf Of > Wander Lairson Costa > Sent: Wednesday, December 4, 2024 12:42 PM > To: Nguyen, Anthony L <anthony.l.nguyen@intel.com>; Kitszel, Przemyslaw > <przemyslaw.kitszel@intel.com>; Andrew Lunn <andrew+netdev@lunn.ch>; > David S. Miller <davem@davemloft.net>; Eric Dumazet > <edumazet@google.com>; Jakub Kicinski <kuba@kernel.org>; Paolo Abeni > <pabeni@redhat.com>; Sebastian Andrzej Siewior <bigeasy@linutronix.de>; Clark > Williams <clrkwllms@kernel.org>; Steven Rostedt <rostedt@goodmis.org>; Auke > Kok <auke-jan.h.kok@intel.com>; Jeff Garzik <jgarzik@redhat.com>; moderated > list:INTEL ETHERNET DRIVERS <intel-wired-lan@lists.osuosl.org>; open > list:NETWORKING DRIVERS <netdev@vger.kernel.org>; open list <linux- > kernel@vger.kernel.org>; open list:Real-time Linux > (PREEMPT_RT):Keyword:PREEMPT_RT <linux-rt-devel@lists.linux.dev> > Cc: Wander Lairson Costa <wander@redhat.com> > Subject: [Intel-wired-lan] [PATCH iwl-net 1/4] igb: narrow scope of vfs_lock in SR- > IOV cleanup > > The adapter->vfs_lock currently protects critical sections shared between > igb_disable_sriov() and igb_msg_task(). Since igb_msg_task() — which is invoked > solely by the igb_msix_other() ISR—only proceeds when > adapter->vfs_allocated_count > 0, we can reduce the lock scope further. > > By moving the assignment adapter->vfs_allocated_count = 0 to the start of the > cleanup code in igb_disable_sriov(), we can restrict the spinlock protection solely > to this assignment. This change removes kfree() calls from within the locked > section, simplifying lock management. > > Once kfree() is outside the vfs_lock scope, it becomes possible to safely convert > vfs_lock to a raw_spin_lock. > > Signed-off-by: Wander Lairson Costa <wander@redhat.com> > --- > drivers/net/ethernet/intel/igb/igb_main.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/net/ethernet/intel/igb/igb_main.c > b/drivers/net/ethernet/intel/igb/igb_main.c > index 08578980b6518..4ca25660e876e 100644 > --- a/drivers/net/ethernet/intel/igb/igb_main.c > +++ b/drivers/net/ethernet/intel/igb/igb_main.c > @@ -3708,12 +3708,12 @@ static int igb_disable_sriov(struct pci_dev *pdev, Tested-by: Rafal Romanowski <rafal.romanowski@intel.com>
diff --git a/drivers/net/ethernet/intel/igb/igb_main.c b/drivers/net/ethernet/intel/igb/igb_main.c index 08578980b6518..4ca25660e876e 100644 --- a/drivers/net/ethernet/intel/igb/igb_main.c +++ b/drivers/net/ethernet/intel/igb/igb_main.c @@ -3708,12 +3708,12 @@ static int igb_disable_sriov(struct pci_dev *pdev, bool reinit) msleep(500); } spin_lock_irqsave(&adapter->vfs_lock, flags); + adapter->vfs_allocated_count = 0; + spin_unlock_irqrestore(&adapter->vfs_lock, flags); kfree(adapter->vf_mac_list); adapter->vf_mac_list = NULL; kfree(adapter->vf_data); adapter->vf_data = NULL; - adapter->vfs_allocated_count = 0; - spin_unlock_irqrestore(&adapter->vfs_lock, flags); wr32(E1000_IOVCTL, E1000_IOVCTL_REUSE_VFQ); wrfl(); msleep(100);
The adapter->vfs_lock currently protects critical sections shared between igb_disable_sriov() and igb_msg_task(). Since igb_msg_task() — which is invoked solely by the igb_msix_other() ISR—only proceeds when adapter->vfs_allocated_count > 0, we can reduce the lock scope further. By moving the assignment adapter->vfs_allocated_count = 0 to the start of the cleanup code in igb_disable_sriov(), we can restrict the spinlock protection solely to this assignment. This change removes kfree() calls from within the locked section, simplifying lock management. Once kfree() is outside the vfs_lock scope, it becomes possible to safely convert vfs_lock to a raw_spin_lock. Signed-off-by: Wander Lairson Costa <wander@redhat.com> --- drivers/net/ethernet/intel/igb/igb_main.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)