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(109-252-153-31.dynamic.spd-mgts.ru [109.252.153.31]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: dmitry.osipenko) by madras.collabora.co.uk (Postfix) with ESMTPSA id 5255D6607354; Fri, 15 Sep 2023 00:29:07 +0100 (BST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1694734149; bh=Ux87TxMV5vy/PWBLrg20A7F+FmVwQrERrTwLmwymf+I=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=hcNyh7i8Q+Xk31Yh4mvNe9RQ4U/F+y1VwR034qHizz3ONttTiuRyiEKmvUpWZH/tB zlY6BqCDg4cyoR2LVRmGC5eI5eYOr2G4GwiRDy2AwOMHW4gQdMTsHYul43o5n69uyt fwdUxkb8A2tTiHV+zgnAQAMVUfFmgsWDUFM3XCNAJXEbZ3ILZk7FCqENJcZYJ4TFoI 5/FWIwUP62pc8RdyYKcOR+DYsMcYjmhioyhqLYC7RxQ4IMBPgnrET6ZWcuL8NSY+bV ZRdnphvYM8fsa4vfISnkzGSie0FzJFUxwec3tPFFH7EwpMjt1aBD2hlg0ysDYFBIuR bhxcBMYxk9Ptg== From: Dmitry Osipenko To: David Airlie , Gerd Hoffmann , Gurchetan Singh , Chia-I Wu , Daniel Vetter , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , =?utf-8?q?Christian_K=C3=B6nig?= , Qiang Yu , Steven Price , Boris Brezillon , Emma Anholt , Melissa Wen Cc: dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, kernel@collabora.com, virtualization@lists.linux-foundation.org Subject: [PATCH v17 08/18] drm/shmem-helper: Add and use lockless drm_gem_shmem_get_pages() Date: Fri, 15 Sep 2023 02:27:11 +0300 Message-ID: <20230914232721.408581-9-dmitry.osipenko@collabora.com> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230914232721.408581-1-dmitry.osipenko@collabora.com> References: <20230914232721.408581-1-dmitry.osipenko@collabora.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-Greylist: Sender passed SPF test, not delayed by milter-greylist-4.6.4 (howler.vger.email [0.0.0.0]); Thu, 14 Sep 2023 16:29:31 -0700 (PDT) X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1777083219058267837 X-GMAIL-MSGID: 1777083219058267837 Add lockless drm_gem_shmem_get_pages() helper that skips taking reservation lock if pages_use_count is non-zero, leveraging from atomicity of the refcount_t. Make drm_gem_shmem_mmap() to utilize the new helper. Reviewed-by: Boris Brezillon Suggested-by: Boris Brezillon Signed-off-by: Dmitry Osipenko --- drivers/gpu/drm/drm_gem_shmem_helper.c | 19 +++++++++++++++---- 1 file changed, 15 insertions(+), 4 deletions(-) diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c index e9d9fbd52b34..a5964f347dda 100644 --- a/drivers/gpu/drm/drm_gem_shmem_helper.c +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c @@ -225,6 +225,20 @@ void drm_gem_shmem_put_pages_locked(struct drm_gem_shmem_object *shmem) } EXPORT_SYMBOL_GPL(drm_gem_shmem_put_pages_locked); +static int drm_gem_shmem_get_pages(struct drm_gem_shmem_object *shmem) +{ + int ret; + + if (refcount_inc_not_zero(&shmem->pages_use_count)) + return 0; + + dma_resv_lock(shmem->base.resv, NULL); + ret = drm_gem_shmem_get_pages_locked(shmem); + dma_resv_unlock(shmem->base.resv); + + return ret; +} + static int drm_gem_shmem_pin_locked(struct drm_gem_shmem_object *shmem) { int ret; @@ -608,10 +622,7 @@ int drm_gem_shmem_mmap(struct drm_gem_shmem_object *shmem, struct vm_area_struct return ret; } - dma_resv_lock(shmem->base.resv, NULL); - ret = drm_gem_shmem_get_pages_locked(shmem); - dma_resv_unlock(shmem->base.resv); - + ret = drm_gem_shmem_get_pages(shmem); if (ret) return ret;