On 01/07/2019 11:53 AM, StDenis, Tom wrote: > On 2019-01-07 11:51 a.m., Grodzovsky, Andrey wrote: >> >> On 01/07/2019 11:36 AM, StDenis, Tom wrote: >>> On 2019-01-07 11:33 a.m., Grodzovsky, Andrey wrote: >>>> On 01/07/2019 11:16 AM, Liu, Shaoyun wrote: >>>>> I think it's reasonable to use the hive specific lock for hive specific functions. >>>>> The changes is acked-by Shaoyun.liu < Shaoyun.liu@xxxxxxx> >>>>> >>>>> -----Original Message----- >>>>> From: amd-gfx <amd-gfx-bounces@xxxxxxxxxxxxxxxxxxxxx> On Behalf Of StDenis, Tom >>>>> Sent: Monday, January 7, 2019 10:16 AM >>>>> To: amd-gfx@xxxxxxxxxxxxxxxxxxxxx >>>>> Cc: StDenis, Tom <Tom.StDenis@xxxxxxx> >>>>> Subject: [PATCH] add missing mutex lock to amdgpu_get_xgmi_hive() (v2) >>>>> >>>>> v2: Move locks around in other functions so that this function can stand on its own. Also only hold the hive specific lock for add/remove device instead of the driver global lock so you can't add/remove devices in parallel from one hive. >>>>> >>>>> Signed-off-by: Tom St Denis <tom.stdenis@xxxxxxx> >>>>> --- >>>>> drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 2 +- >>>>> drivers/gpu/drm/amd/amdgpu/amdgpu_xgmi.c | 36 ++++++++++++++-------- >>>>> drivers/gpu/drm/amd/amdgpu/amdgpu_xgmi.h | 2 +- >>>>> 3 files changed, 25 insertions(+), 15 deletions(-) >>>>> >>>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c >>>>> index 39d5d058b2c7..13d8e2ad2f7a 100644 >>>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c >>>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c >>>>> @@ -3525,7 +3525,7 @@ int amdgpu_device_gpu_recover(struct amdgpu_device *adev, >>>>> * by different nodes. No point also since the one node already executing >>>>> * reset will also reset all the other nodes in the hive. >>>>> */ >>>>> - hive = amdgpu_get_xgmi_hive(adev); >>>>> + hive = amdgpu_get_xgmi_hive(adev, 0); >>>>> if (hive && adev->gmc.xgmi.num_physical_nodes > 1 && >>>>> !mutex_trylock(&hive->hive_lock)) >>>>> return 0; >>>> Let's say i have device 0 in hive A and it just got a gpu reset and at >>>> the same time device 1 is being added to same have though >>>> amdgpu_xgmi_add_device, hive->hive_lock is acquired by this new device >>>> being added and so gpu reset for device 0 bails out on >>>> '!mutex_trylock(&hive->hive_lock))' without completing the reset. >>>> Also in general i feel a bit uncomfortable about the confusing >>>> acquisition scheme in the function and the fact that you take the >>>> hive->hive_lock inside amdgpu_get_xgmi_hive but release is still outside >>>> of the function. >>> Is adding a device while resetting a device even a valid operation >>> anyways? >> In theory it's valid if you have hot pluggable devices >>> I think this means more so that the reset logic is broken. Instead >>> there should be a per-hive reset lock that is taken and that is tested >>> instead. >>> >>> Tom >> The hive->hive_lock was added exactly for this purpose and used only for >> that purpose. Maybe the naming i gave it wasn't reflective of it's >> purpose :) > > But the add/remove should use per-hive locks not the global lock... :-) > > (I'm honestly not trying to bike shed I just thought the get_hive > function looked wrong :-)). > > Tom Totally agree with you, if Shayun (who origianlly added the global xgmi_mutex) is fine with switching to per hive mutex then me too, I just point out the problem with gpu reset and as you said we then need to rename the existing hive_lock into reset_lock and then and another per hive lock to do what you propose. Also - is there a way to not take the hive lock inside amdgpu_get_xgmi_hive but release it outside ? AFAIK it's an opening for problems where people use it but forget to call release. Andrey > _______________________________________________ > amd-gfx mailing list > amd-gfx@xxxxxxxxxxxxxxxxxxxxx > https://lists.freedesktop.org/mailman/listinfo/amd-gfx _______________________________________________ amd-gfx mailing list amd-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/amd-gfx
