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[2a02:3100:b13f:501:c85b:b4b7:2475:2549]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4a1d756ce69sm140854855e9.4.2026.10.18.10.56.21 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Sun, 18 Oct 2026 10:56:22 -0700 (PDT) From: Karl Mehltretter To: Vinod Koul , dmaengine@vger.kernel.org Cc: Karl Mehltretter , Frank Li , Dan Williams , linux-kernel@vger.kernel.org Subject: [PATCH] dmaengine: dmatest: make wait parameter reads interruptible Date: Sun, 18 Oct 2026 19:56:06 +0200 Message-Id: <20261018175606.38045-1-kmehltretter@gmail.com> X-Mailer: git-send-email 2.39.5 (Apple Git-154) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Reading the wait parameter during a finite test uses wait_event(). The reader remains in uninterruptible sleep until all test threads finish. Long runs trigger the hung-task detector, and signals cannot stop the reader: INFO: task cat:71690 blocked for more than 120 seconds. Call trace: dmatest_wait_get+0x17c/0x1d8 [dmatest] param_attr_show+0x6c/0xb0 Use wait_event_interruptible() and propagate the signal error so Ctrl-C and timeout can abort the sysfs read. The test threads continue independently. On a Raspberry Pi 500+ RP1 DMA channel, a script configured dmatest with 1 MiB buffers and two threads of 2,000 iterations each. The unpatched run completed all 4,000 tests without failures in 267 seconds, but emitted hung-task reports at 120 and 241 seconds. With the patch, the same 4,000 tests completed without failures in 269 seconds and emitted no hung-task report. In a separate patched run, SIGTERM terminated the reader. Both test threads continued and completed all 200 tests without failures. Fixes: 2d88ce76eb98 ("dmatest: add a 'wait' parameter") Assisted-by: LLM Signed-off-by: Karl Mehltretter --- drivers/dma/dmatest.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/drivers/dma/dmatest.c b/drivers/dma/dmatest.c index 2ae346939..7e6b6c446 100644 --- a/drivers/dma/dmatest.c +++ b/drivers/dma/dmatest.c @@ -287,9 +287,14 @@ static int dmatest_wait_get(char *val, const struct kernel_param *kp) { struct dmatest_info *info = &test_info; struct dmatest_params *params = &info->params; + int ret; - if (params->iterations) - wait_event(thread_wait, !is_threaded_test_run(info)); + if (params->iterations) { + ret = wait_event_interruptible(thread_wait, + !is_threaded_test_run(info)); + if (ret) + return ret; + } wait = true; return param_get_bool(val, kp); } -- 2.39.5 (Apple Git-154)