From mboxrd@z Thu Jan 1 00:00:00 1970 From: jglisse@redhat.com Subject: [PATCH] dma-buf: fix debugfs versus rcu and fence dumping Date: Wed, 5 Dec 2018 20:41:03 -0500 Message-ID: <20181206014103.1364-1-jglisse@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Return-path: Sender: stable-owner@vger.kernel.org To: linux-kernel@vger.kernel.org Cc: =?UTF-8?q?J=C3=A9r=C3=B4me=20Glisse?= , =?UTF-8?q?Christian=20K=C3=B6nig?= , Daniel Vetter , Sumit Semwal , linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, =?UTF-8?q?St=C3=A9phane=20Marchesin?= , stable@vger.kernel.org List-Id: dri-devel@lists.freedesktop.org From: Jérôme Glisse The debugfs take reference on fence without dropping them. Also the rcu section are not well balance. Fix all that ... Signed-off-by: Jérôme Glisse Cc: Christian König Cc: Daniel Vetter Cc: Sumit Semwal Cc: linux-media@vger.kernel.org Cc: dri-devel@lists.freedesktop.org Cc: linaro-mm-sig@lists.linaro.org Cc: Stéphane Marchesin Cc: stable@vger.kernel.org --- drivers/dma-buf/dma-buf.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c index 13884474d158..f6f4de42ac49 100644 --- a/drivers/dma-buf/dma-buf.c +++ b/drivers/dma-buf/dma-buf.c @@ -1051,24 +1051,31 @@ static int dma_buf_debug_show(struct seq_file *s, void *unused) fobj = rcu_dereference(robj->fence); shared_count = fobj ? fobj->shared_count : 0; fence = rcu_dereference(robj->fence_excl); + fence = dma_fence_get_rcu(fence); if (!read_seqcount_retry(&robj->seq, seq)) break; rcu_read_unlock(); } - - if (fence) + if (fence) { seq_printf(s, "\tExclusive fence: %s %s %ssignalled\n", fence->ops->get_driver_name(fence), fence->ops->get_timeline_name(fence), dma_fence_is_signaled(fence) ? "" : "un"); + dma_fence_put(fence); + } + + rcu_read_lock(); for (i = 0; i < shared_count; i++) { fence = rcu_dereference(fobj->shared[i]); if (!dma_fence_get_rcu(fence)) continue; + rcu_read_unlock(); seq_printf(s, "\tShared fence: %s %s %ssignalled\n", fence->ops->get_driver_name(fence), fence->ops->get_timeline_name(fence), dma_fence_is_signaled(fence) ? "" : "un"); + dma_fence_put(fence); + rcu_read_lock(); } rcu_read_unlock(); -- 2.17.2