| Message ID | 20211125174200.133230-1-mst@redhat.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | Bluetooth: virtio_bt: fix device removal | expand |
On Thu, Nov 25, 2021 at 09:02:01PM +0100, Marcel Holtmann wrote: > Hi Michael, > > > Device removal is clearly out of virtio spec: it attempts to remove > > unused buffers from a VQ before invoking device reset. To fix, make > > open/close NOPs and do all cleanup/setup in probe/remove. > > so the virtbt_{open,close} as NOP is not really what a driver is suppose > to be doing. These are transport enable/disable callbacks from the BT > Core towards the driver. It maps to a device being enabled/disabled by > something like bluetoothd for example. So if disabled, I expect that no > resources/queues are in use. > > Maybe I misunderstand the virtio spec in that regard, but I would like > to keep this fundamental concept of a Bluetooth driver. It does work > with all other transports like USB, SDIO, UART etc. > > > The cost here is a single skb wasted on an unused bt device - which > > seems modest. > > There should be no buffer used if the device is powered off. We also don’t > have any USB URBs in-flight if the transport is not active. > > > NB: with this fix in place driver still suffers from a race condition if > > an interrupt triggers while device is being reset. Work on a fix for > > that issue is in progress. > > In the virtbt_close() callback we should deactivate all interrupts. > > Regards > > Marcel So Marcel, do I read it right that you are working on a fix and I can drop this patch for now?
On Thu, Dec 09, 2021 at 04:22:58PM -0500, Michael S. Tsirkin wrote: > On Thu, Nov 25, 2021 at 09:02:01PM +0100, Marcel Holtmann wrote: > > Hi Michael, > > > > > Device removal is clearly out of virtio spec: it attempts to remove > > > unused buffers from a VQ before invoking device reset. To fix, make > > > open/close NOPs and do all cleanup/setup in probe/remove. > > > > so the virtbt_{open,close} as NOP is not really what a driver is suppose > > to be doing. These are transport enable/disable callbacks from the BT > > Core towards the driver. It maps to a device being enabled/disabled by > > something like bluetoothd for example. So if disabled, I expect that no > > resources/queues are in use. > > > > Maybe I misunderstand the virtio spec in that regard, but I would like > > to keep this fundamental concept of a Bluetooth driver. It does work > > with all other transports like USB, SDIO, UART etc. > > > > > The cost here is a single skb wasted on an unused bt device - which > > > seems modest. > > > > There should be no buffer used if the device is powered off. We also don’t > > have any USB URBs in-flight if the transport is not active. > > > > > NB: with this fix in place driver still suffers from a race condition if > > > an interrupt triggers while device is being reset. Work on a fix for > > > that issue is in progress. > > > > In the virtbt_close() callback we should deactivate all interrupts. > > > > Regards > > > > Marcel > > So Marcel, do I read it right that you are working on a fix > and I can drop this patch for now? ping > -- > MST
On Mon, Dec 13, 2021 at 05:44:13AM -0500, Michael S. Tsirkin wrote: > On Thu, Dec 09, 2021 at 04:22:58PM -0500, Michael S. Tsirkin wrote: > > On Thu, Nov 25, 2021 at 09:02:01PM +0100, Marcel Holtmann wrote: > > > Hi Michael, > > > > > > > Device removal is clearly out of virtio spec: it attempts to remove > > > > unused buffers from a VQ before invoking device reset. To fix, make > > > > open/close NOPs and do all cleanup/setup in probe/remove. > > > > > > so the virtbt_{open,close} as NOP is not really what a driver is suppose > > > to be doing. These are transport enable/disable callbacks from the BT > > > Core towards the driver. It maps to a device being enabled/disabled by > > > something like bluetoothd for example. So if disabled, I expect that no > > > resources/queues are in use. > > > > > > Maybe I misunderstand the virtio spec in that regard, but I would like > > > to keep this fundamental concept of a Bluetooth driver. It does work > > > with all other transports like USB, SDIO, UART etc. > > > > > > > The cost here is a single skb wasted on an unused bt device - which > > > > seems modest. > > > > > > There should be no buffer used if the device is powered off. We also don’t > > > have any USB URBs in-flight if the transport is not active. > > > > > > > NB: with this fix in place driver still suffers from a race condition if > > > > an interrupt triggers while device is being reset. Work on a fix for > > > > that issue is in progress. > > > > > > In the virtbt_close() callback we should deactivate all interrupts. > > > > > > Regards > > > > > > Marcel > > > > So Marcel, do I read it right that you are working on a fix > > and I can drop this patch for now? > > ping If I don't hear otherwise I'll queue my version - it might not be ideal but it at least does not violate the spec. We can work on not allocating/freeing buffers later as appropriate. > > -- > > MST
Hi Michael, >>>>> Device removal is clearly out of virtio spec: it attempts to remove >>>>> unused buffers from a VQ before invoking device reset. To fix, make >>>>> open/close NOPs and do all cleanup/setup in probe/remove. >>>> >>>> so the virtbt_{open,close} as NOP is not really what a driver is suppose >>>> to be doing. These are transport enable/disable callbacks from the BT >>>> Core towards the driver. It maps to a device being enabled/disabled by >>>> something like bluetoothd for example. So if disabled, I expect that no >>>> resources/queues are in use. >>>> >>>> Maybe I misunderstand the virtio spec in that regard, but I would like >>>> to keep this fundamental concept of a Bluetooth driver. It does work >>>> with all other transports like USB, SDIO, UART etc. >>>> >>>>> The cost here is a single skb wasted on an unused bt device - which >>>>> seems modest. >>>> >>>> There should be no buffer used if the device is powered off. We also don’t >>>> have any USB URBs in-flight if the transport is not active. >>>> >>>>> NB: with this fix in place driver still suffers from a race condition if >>>>> an interrupt triggers while device is being reset. Work on a fix for >>>>> that issue is in progress. >>>> >>>> In the virtbt_close() callback we should deactivate all interrupts. >>>> >>>> Regards >>>> >>>> Marcel >>> >>> So Marcel, do I read it right that you are working on a fix >>> and I can drop this patch for now? >> >> ping > > > If I don't hear otherwise I'll queue my version - it might not > be ideal but it at least does not violate the spec. > We can work on not allocating/freeing buffers later > as appropriate. I have a patch, but it is not fully tested yet. Regards Marcel
On Thu, Dec 16, 2021 at 08:58:31PM +0100, Marcel Holtmann wrote: > Hi Michael, > > >>>>> Device removal is clearly out of virtio spec: it attempts to remove > >>>>> unused buffers from a VQ before invoking device reset. To fix, make > >>>>> open/close NOPs and do all cleanup/setup in probe/remove. > >>>> > >>>> so the virtbt_{open,close} as NOP is not really what a driver is suppose > >>>> to be doing. These are transport enable/disable callbacks from the BT > >>>> Core towards the driver. It maps to a device being enabled/disabled by > >>>> something like bluetoothd for example. So if disabled, I expect that no > >>>> resources/queues are in use. > >>>> > >>>> Maybe I misunderstand the virtio spec in that regard, but I would like > >>>> to keep this fundamental concept of a Bluetooth driver. It does work > >>>> with all other transports like USB, SDIO, UART etc. > >>>> > >>>>> The cost here is a single skb wasted on an unused bt device - which > >>>>> seems modest. > >>>> > >>>> There should be no buffer used if the device is powered off. We also don’t > >>>> have any USB URBs in-flight if the transport is not active. > >>>> > >>>>> NB: with this fix in place driver still suffers from a race condition if > >>>>> an interrupt triggers while device is being reset. Work on a fix for > >>>>> that issue is in progress. > >>>> > >>>> In the virtbt_close() callback we should deactivate all interrupts. > >>>> > >>>> Regards > >>>> > >>>> Marcel > >>> > >>> So Marcel, do I read it right that you are working on a fix > >>> and I can drop this patch for now? > >> > >> ping > > > > > > If I don't hear otherwise I'll queue my version - it might not > > be ideal but it at least does not violate the spec. > > We can work on not allocating/freeing buffers later > > as appropriate. > > I have a patch, but it is not fully tested yet. > > Regards > > Marcel ping it's been a month ... I'm working on cleaning up module/device removal in virtio and bt is kind of sticking out.
On Fri, Jan 14, 2022 at 03:12:47PM -0500, Michael S. Tsirkin wrote: > On Thu, Dec 16, 2021 at 08:58:31PM +0100, Marcel Holtmann wrote: > > Hi Michael, > > > > >>>>> Device removal is clearly out of virtio spec: it attempts to remove > > >>>>> unused buffers from a VQ before invoking device reset. To fix, make > > >>>>> open/close NOPs and do all cleanup/setup in probe/remove. > > >>>> > > >>>> so the virtbt_{open,close} as NOP is not really what a driver is suppose > > >>>> to be doing. These are transport enable/disable callbacks from the BT > > >>>> Core towards the driver. It maps to a device being enabled/disabled by > > >>>> something like bluetoothd for example. So if disabled, I expect that no > > >>>> resources/queues are in use. > > >>>> > > >>>> Maybe I misunderstand the virtio spec in that regard, but I would like > > >>>> to keep this fundamental concept of a Bluetooth driver. It does work > > >>>> with all other transports like USB, SDIO, UART etc. > > >>>> > > >>>>> The cost here is a single skb wasted on an unused bt device - which > > >>>>> seems modest. > > >>>> > > >>>> There should be no buffer used if the device is powered off. We also don’t > > >>>> have any USB URBs in-flight if the transport is not active. > > >>>> > > >>>>> NB: with this fix in place driver still suffers from a race condition if > > >>>>> an interrupt triggers while device is being reset. Work on a fix for > > >>>>> that issue is in progress. > > >>>> > > >>>> In the virtbt_close() callback we should deactivate all interrupts. > > >>>> > > >>>> Regards > > >>>> > > >>>> Marcel > > >>> > > >>> So Marcel, do I read it right that you are working on a fix > > >>> and I can drop this patch for now? > > >> > > >> ping > > > > > > > > > If I don't hear otherwise I'll queue my version - it might not > > > be ideal but it at least does not violate the spec. > > > We can work on not allocating/freeing buffers later > > > as appropriate. > > > > I have a patch, but it is not fully tested yet. > > > > Regards > > > > Marcel > > ping > > it's been a month ... > > I'm working on cleaning up module/device removal in virtio and bt > is kind of sticking out. I am inclined to make this driver depend on BROKEN for now. Any objections? > -- > MST
On Mon, Jun 13, 2022 at 02:58:59AM -0400, Michael S. Tsirkin wrote: > On Fri, Jan 14, 2022 at 03:12:47PM -0500, Michael S. Tsirkin wrote: > > On Thu, Dec 16, 2021 at 08:58:31PM +0100, Marcel Holtmann wrote: > > > Hi Michael, > > > > > > >>>>> Device removal is clearly out of virtio spec: it attempts to remove > > > >>>>> unused buffers from a VQ before invoking device reset. To fix, make > > > >>>>> open/close NOPs and do all cleanup/setup in probe/remove. > > > >>>> > > > >>>> so the virtbt_{open,close} as NOP is not really what a driver is suppose > > > >>>> to be doing. These are transport enable/disable callbacks from the BT > > > >>>> Core towards the driver. It maps to a device being enabled/disabled by > > > >>>> something like bluetoothd for example. So if disabled, I expect that no > > > >>>> resources/queues are in use. > > > >>>> > > > >>>> Maybe I misunderstand the virtio spec in that regard, but I would like > > > >>>> to keep this fundamental concept of a Bluetooth driver. It does work > > > >>>> with all other transports like USB, SDIO, UART etc. > > > >>>> > > > >>>>> The cost here is a single skb wasted on an unused bt device - which > > > >>>>> seems modest. > > > >>>> > > > >>>> There should be no buffer used if the device is powered off. We also don’t > > > >>>> have any USB URBs in-flight if the transport is not active. > > > >>>> > > > >>>>> NB: with this fix in place driver still suffers from a race condition if > > > >>>>> an interrupt triggers while device is being reset. Work on a fix for > > > >>>>> that issue is in progress. > > > >>>> > > > >>>> In the virtbt_close() callback we should deactivate all interrupts. > > > >>>> > > > >>>> Regards > > > >>>> > > > >>>> Marcel > > > >>> > > > >>> So Marcel, do I read it right that you are working on a fix > > > >>> and I can drop this patch for now? > > > >> > > > >> ping > > > > > > > > > > > > If I don't hear otherwise I'll queue my version - it might not > > > > be ideal but it at least does not violate the spec. > > > > We can work on not allocating/freeing buffers later > > > > as appropriate. > > > > > > I have a patch, but it is not fully tested yet. > > > > > > Regards > > > > > > Marcel > > > > ping > > > > it's been a month ... > > > > I'm working on cleaning up module/device removal in virtio and bt > > is kind of sticking out. > > I am inclined to make this driver depend on BROKEN for now. > Any objections? OK patch incoming. > > > -- > > MST
diff --git a/drivers/bluetooth/virtio_bt.c b/drivers/bluetooth/virtio_bt.c index 24a9258962fa..aea33ba9522c 100644 --- a/drivers/bluetooth/virtio_bt.c +++ b/drivers/bluetooth/virtio_bt.c @@ -50,8 +50,11 @@ static int virtbt_add_inbuf(struct virtio_bluetooth *vbt) static int virtbt_open(struct hci_dev *hdev) { - struct virtio_bluetooth *vbt = hci_get_drvdata(hdev); + return 0; +} +static int virtbt_open_vdev(struct virtio_bluetooth *vbt) +{ if (virtbt_add_inbuf(vbt) < 0) return -EIO; @@ -61,7 +64,11 @@ static int virtbt_open(struct hci_dev *hdev) static int virtbt_close(struct hci_dev *hdev) { - struct virtio_bluetooth *vbt = hci_get_drvdata(hdev); + return 0; +} + +static int virtbt_close_vdev(struct virtio_bluetooth *vbt) +{ int i; cancel_work_sync(&vbt->rx); @@ -351,8 +358,14 @@ static int virtbt_probe(struct virtio_device *vdev) goto failed; } + virtio_device_ready(vdev); + if (virtbt_open_vdev(vbt)) + goto open_failed; + return 0; +open_failed: + hci_free_dev(hdev); failed: vdev->config->del_vqs(vdev); return err; @@ -365,6 +378,7 @@ static void virtbt_remove(struct virtio_device *vdev) hci_unregister_dev(hdev); vdev->config->reset(vdev); + virtbt_close_vdev(vbt); hci_free_dev(hdev); vbt->hdev = NULL;
Device removal is clearly out of virtio spec: it attempts to remove unused buffers from a VQ before invoking device reset. To fix, make open/close NOPs and do all cleanup/setup in probe/remove. The cost here is a single skb wasted on an unused bt device - which seems modest. NB: with this fix in place driver still suffers from a race condition if an interrupt triggers while device is being reset. Work on a fix for that issue is in progress. Signed-off-by: Michael S. Tsirkin <mst@redhat.com> --- Note: completely untested, in particular the device isn't supported in QEMU. Please do not queue directly - please help review and test and ack, and I will queue this together with reset fixes. Thanks! drivers/bluetooth/virtio_bt.c | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-)