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Message-ID: <84a5f7b6-d20a-4c69-83a8-d8394fea2b68@suse.de>
Date: Thu, 2 May 2024 13:51:16 +0200
From: Thomas Zimmermann <tzimmermann@...e.de>
To: Adrián Larumbe <adrian.larumbe@...labora.com>,
Qiang Yu <yuq825@...il.com>,
Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
Maxime Ripard <mripard@...nel.org>, David Airlie <airlied@...il.com>,
Daniel Vetter <daniel@...ll.ch>,
Boris Brezillon <boris.brezillon@...labora.com>,
Rob Herring <robh@...nel.org>, Steven Price <steven.price@....com>,
Sumit Semwal <sumit.semwal@...aro.org>,
Christian Koenig= <christian.koenig@....com>,
Dmitry Osipenko <dmitry.osipenko@...labora.com>,
Zack Rusin <zack.rusin@...adcom.com>
Cc: kernel@...labora.com, dri-devel@...ts.freedesktop.org,
lima@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
linux-media@...r.kernel.org, linaro-mm-sig@...ts.linaro.org
Subject: Re: [PATCH v3 0/2] drm: Fix dma_resv deadlock at drm object pin time
Hi,
ignoring my r-b on patch 1, I'd like to rethink the current patches in
general.
I think drm_gem_shmem_pin() should become the locked version of _pin(),
so that drm_gem_shmem_object_pin() can call it directly. The existing
_pin_unlocked() would not be needed any longer. Same for the _unpin()
functions. This change would also fix the consistency with the semantics
of the shmem _vmap() functions, which never take reservation locks.
There are only two external callers of drm_gem_shmem_pin(): the test
case and panthor. These assume that drm_gem_shmem_pin() acquires the
reservation lock. The test case should likely call drm_gem_pin()
instead. That would acquire the reservation lock and the test would
validate that shmem's pin helper integrates well into the overall GEM
framework. The way panthor uses drm_gem_shmem_pin() looks wrong to me.
For now, it could receive a wrapper that takes the lock and that's it.
Best regards
Thomas
Am 01.05.24 um 08:55 schrieb Adrián Larumbe:
> This is v3 of https://lore.kernel.org/dri-devel/20240424090429.57de7d1c@collabora.com/
>
> The goal of this patch series is fixing a deadlock upon locking the dma reservation
> of a DRM gem object when pinning it, at a prime import operation.
>
> Changes from v2:
> - Removed comment explaining reason why an already-locked
> pin function replaced the locked variant inside Panfrost's
> object pin callback.
> - Moved already-assigned attachment warning into generic
> already-locked gem object pin function
>
> Adrián Larumbe (2):
> drm/panfrost: Fix dma_resv deadlock at drm object pin time
> drm/gem-shmem: Add import attachment warning to locked pin function
>
> drivers/gpu/drm/drm_gem_shmem_helper.c | 2 ++
> drivers/gpu/drm/lima/lima_gem.c | 2 +-
> drivers/gpu/drm/panfrost/panfrost_gem.c | 2 +-
> 3 files changed, 4 insertions(+), 2 deletions(-)
>
>
> base-commit: 75b68f22e39aafb22f3d8e3071e1aba73560788c
--
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)
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