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Commit 55257d72bd1c51f25106350f4983ec19f62ed1fa (virtio-net: fill only rx queues which are being used) tries to refill on demand when changing the number of channels by call try_refill_recv() directly, this may race: - the refill work who may do the refill in the same time - the try_refill_recv() called in bh since napi was not disabled Which may led guest complain during setting channels: virtio_net virtio0: i...

Commit 55257d72bd1c51f25106350f4983ec19f62ed1fa (virtio-net: fill only rx queues which are being used) tries to refill on demand when changing the number of channels by call try_refill_recv() directly, this may race: - the refill work who may do the refill in the same time - the try_refill_recv() called in bh since napi was not disabled Which may led guest complain during setting channels: virtio_net virtio0: i...

Fix theoretical races related to refill work: 1. After napi is disabled by ndo_stop, refill work can run and re-enable it. 2. Refill can reschedule itself, if this happens it can run after cancel_delayed_work_sync, and will access device after it is destroyed. As a solution, add flags to track napi state and to disable refill,...

Fix theoretical races related to refill work: 1. After napi is disabled by ndo_stop, refill work can run and re-enable it. 2. Refill can reschedule itself, if this happens it can run after cancel_delayed_work_sync, and will access device after it is destroyed. As a solution, add flags to track napi state and to disable refill,...

Fix theoretical races related to refill work: 1. After napi is disabled by ndo_stop, refill work can run and re-enable it. 2. Refill can get scheduled on many cpus in parallel. if this happens it will corrupt the vq linked list as there's no locking 3. refill work is cancelled after unregister netdev For small bufs this...

Fix theoretical races related to refill work: 1. After napi is disabled by ndo_stop, refill work can run and re-enable it. 2. Refill can get scheduled on many cpus in parallel. if this happens it will corrupt the vq linked list as there's no locking 3. refill work is cancelled after unregister netdev For small bufs this...

On Mon, Oct 14, 2013 at 05:56:35PM +0800, Jason Wang wrote: > We used to schedule the refill work unconditionally after changing the > number of queues. This may lead an issue if the device is not > up. Since we only try to cancel the work in ndo_stop(), this may cause > the refill work still work after removing the device. Fix this by only > schedule the work when device is u...

On Mon, Oct 14, 2013 at 05:56:35PM +0800, Jason Wang wrote: > We used to schedule the refill work unconditionally after changing the > number of queues. This may lead an issue if the device is not > up. Since we only try to cancel the work in ndo_stop(), this may cause > the refill work still work after removing the device. Fix this by only > schedule the work when device is u...

Please consider this for the 2.6.32 stable tree: commit 39d321577405e8e269fd238b278aaf2425fa788a Author: Herbert Xu <herbert at gondor.apana.org.au> Date: Mon Jan 25 15:51:01 2010 -0800 virtio_net: Make delayed refill more reliable I have seen RX stalls on a machine that experienced a suspected OOM. After the stall, the RX buffer is empty on the guest side and there are exactly 16 entries available on the host side. As the number of entries is less than that required by a maximal skb, the...

Please consider this for the 2.6.32 stable tree: commit 39d321577405e8e269fd238b278aaf2425fa788a Author: Herbert Xu <herbert at gondor.apana.org.au> Date: Mon Jan 25 15:51:01 2010 -0800 virtio_net: Make delayed refill more reliable I have seen RX stalls on a machine that experienced a suspected OOM. After the stall, the RX buffer is empty on the guest side and there are exactly 16 entries available on the host side. As the number of entries is less than that required by a maximal skb, the...

We used to schedule the refill work unconditionally after changing the number of queues. This may lead an issue if the device is not up. Since we only try to cancel the work in ndo_stop(), this may cause the refill work still work after removing the device. Fix this by only schedule the work when device is up. The bug were int...

We used to schedule the refill work unconditionally after changing the number of queues. This may lead an issue if the device is not up. Since we only try to cancel the work in ndo_stop(), this may cause the refill work still work after removing the device. Fix this by only schedule the work when device is up. The bug were int...

...et using just the per-receive page_frags. For future > consideration, Eric noted that disabling NAPI before GFP_KERNEL > allocs can potentially inhibit virtio-net network processing for some > time (e.g., during a blocking memory allocation or preemption). Yep, using napi_disable() in the refill process looks quite inefficient to me, it not buggy. napi_disable() is a big hammer, while whole idea of having a process to block on GFP_KERNEL allocations is to allow some asynchronous behavior. I have hard time to convince myself virtio_net is safe anyway with this work queue thing. virtnet_...

...et using just the per-receive page_frags. For future > consideration, Eric noted that disabling NAPI before GFP_KERNEL > allocs can potentially inhibit virtio-net network processing for some > time (e.g., during a blocking memory allocation or preemption). Yep, using napi_disable() in the refill process looks quite inefficient to me, it not buggy. napi_disable() is a big hammer, while whole idea of having a process to block on GFP_KERNEL allocations is to allow some asynchronous behavior. I have hard time to convince myself virtio_net is safe anyway with this work queue thing. virtnet_...

On Thu, Dec 29, 2011 at 09:12:38PM +1030, Rusty Russell wrote: > Michael S. Tsirkin noticed that we could run the refill work after > ndo_close, which can re-enable napi - we don't disable it until > virtnet_remove. This is clearly wrong, so move the workqueue control > to ndo_open and ndo_stop (aka. virtnet_open and virtnet_close). > > One subtle point: virtnet_probe() could simply fail if it c...

On Thu, Dec 29, 2011 at 09:12:38PM +1030, Rusty Russell wrote: > Michael S. Tsirkin noticed that we could run the refill work after > ndo_close, which can re-enable napi - we don't disable it until > virtnet_remove. This is clearly wrong, so move the workqueue control > to ndo_open and ndo_stop (aka. virtnet_open and virtnet_close). > > One subtle point: virtnet_probe() could simply fail if it c...

To even the latency, refill buffer right after being used. Sign-off-by: Shirley Ma <xma at us.ibm.com> --- diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index 0c7321c..c8201d4 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -429,6 +429,22 @@ static int add_recvbuf_mergeable(...

To even the latency, refill buffer right after being used. Sign-off-by: Shirley Ma <xma at us.ibm.com> --- diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c index 0c7321c..c8201d4 100644 --- a/drivers/net/virtio_net.c +++ b/drivers/net/virtio_net.c @@ -429,6 +429,22 @@ static int add_recvbuf_mergeable(...

During restoring, try_fill_recv() was called with neither napi lock nor napi disabled. This can lead two try_fill_recv() was called in the same time. Fix this by refilling before trying to enable napi. Fixes 0741bcb5584f9e2390ae6261573c4de8314999f2 (virtio: net: Add freeze, restore handlers to support S4). Cc: Amit Shah <amit.shah at redhat.com> Cc: Rusty Russell <rusty at rustcorp.com.au> Cc: Michael S. Tsirkin <mst at redhat.com> Cc: Eric Du...

During restoring, try_fill_recv() was called with neither napi lock nor napi disabled. This can lead two try_fill_recv() was called in the same time. Fix this by refilling before trying to enable napi. Fixes 0741bcb5584f9e2390ae6261573c4de8314999f2 (virtio: net: Add freeze, restore handlers to support S4). Cc: Amit Shah <amit.shah at redhat.com> Cc: Rusty Russell <rusty at rustcorp.com.au> Cc: Michael S. Tsirkin <mst at redhat.com> Cc: Eric Du...