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Mon, 19 Oct 2026 00:25:42 -0700 (PDT) X-Received: by 2002:a05:7301:2a9b:b0:35f:6d9d:af68 with SMTP id 5a478bee46e88-361a1f4fa38mr9834518eec.23.1792394742408; Mon, 19 Oct 2026 00:25:42 -0700 (PDT) Received: from [192.168.1.7] ([101.0.62.42]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-3608258aa66sm37292247eec.20.2026.10.19.00.25.38 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 19 Oct 2026 00:25:41 -0700 (PDT) Message-ID: Date: Mon, 19 Oct 2026 12:55:37 +0530 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v1 2/3] misc: fastrpc: wake poll-mode waiters on SSR To: Jianping Li , Srinivas Kandagatla Cc: Arnd Bergmann , Greg Kroah-Hartman , Thierry Escande , linux-arm-msm@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, quic_chennak@quicinc.com References: <20261007084447.922-1-jianping.li@oss.qualcomm.com> <20261007084447.922-3-jianping.li@oss.qualcomm.com> Content-Language: en-US From: Ekansh Gupta In-Reply-To: <20261007084447.922-3-jianping.li@oss.qualcomm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Proofpoint-Spam-Info: AW1haW4tMjYxMDE5MDAyOSBTYWx0ZWRfX5i8aQRk3Y3jF sQmb9yJbG24gKW9/VZOovtF3CNAGf0AaW83JfplT0VjT3LpXXgYN3RQEJ0TS8bxZzQbOGMHAO/g l4odoKJKE7QGeMfNPEtyVBWlB/FTBd8= X-Proofpoint-ORIG-GUID: E9S4G0e4Er5Jbt0hoGUKsN5tuyR5eVEs X-Proofpoint-GUID: E9S4G0e4Er5Jbt0hoGUKsN5tuyR5eVEs X-Authority-Analysis: v=2.4 cv=K4O3jCWI c=1 sm=1 tr=0 ts=6ad5c5f8 cx=c_pps a=wEP8DlPgTf/vqF+yE6f9lg==:117 a=sC8K8RXUWm68HHFV/PXcoQ==:17 a=IkcTkHD0fZMA:10 a=660iZSQnnn4A:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=yx91gb_oNiZeI1HMLzn7:22 a=EUspDBNiAAAA:8 a=Ibi0DqZ3yaYieqUivDkA:9 a=QEXdDO2ut3YA:10 a=bBxd6f-gb0O0v-kibOvt:22 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYxMDE5MDAyOSBTYWx0ZWRfX+0djjUBpV3Kc rE5FUYEVXvcf8HaRVvg9Mzg/TM9Yu1GLOGoFpIOawW6ygRiFM31Yk0vlsX0DkGuYUojA/PUwIZo y490gGh0EI6ITWXFyF2Yr6bb8caegxqEnVzrNditKuFHlkxdtgtnRNjwU+6PLaltxrqkI/1Kzl4 XwsKFffARezL06mFaWVrWvffModDxHIyImdsZBJPMGdf3orm5zfQoDIPov/oPUEfKmz9GWKc4y6 8gJaDbddnU9tUit+jdDtsbYKqte3Q4cUJT4UGxBalgh44ATjqsD6UrZd7HEOxsoYOn2oa1IwAZE BZHixg5wbmB5LkXCo4MVQ1AHsvA+DUoHrjLC3B0ZwGGJr/iSeTQNtQHyNFFQ6fMka6Dr4nV8fc8 3x9YmusJX8GNhUe25HkyhRDQa/Zi/0ZIqlFF2yoMtOM3mmhLm8M08XkH2xMPQIR6c5NilorIKaX 60gAT/r/hF/AFKPpBUg== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-10-19_02,2026-10-14_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 spamscore=0 priorityscore=1501 phishscore=0 clxscore=1015 adultscore=0 lowpriorityscore=0 bulkscore=0 malwarescore=0 suspectscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2610080000 definitions=main-2610190029 On 07-10-2026 14:14, Jianping Li wrote: > fastrpc_notify_users() sets ctx->retval to -EPIPE and completes > ctx->work for every pending and interrupted context, which is enough to > release a thread blocked in fastrpc_wait_for_response(). > > A thread using polling mode does not wait on that completion. It spins > in poll_for_remote_response(), whose exit condition is: > > (val == FASTRPC_POLL_RESPONSE) || ctx->is_work_done > > Since the DSP is already down, it will never write FASTRPC_POLL_RESPONSE > into the poll address, and is_work_done is left untouched by > fastrpc_notify_users(). The thread therefore keeps spinning until > FASTRPC_POLL_MAX_TIMEOUT_US expires instead of bailing out immediately. > > Worse, the poll address lives inside ctx->buf, so a polling thread that > has not been told to stop is still reading a buffer that the SSR > teardown path is about to reclaim. > > Set is_work_done along with retval so polling waiters observe the > termination on their next iteration, exactly like completion waiters do. > > Signed-off-by: Jianping Li This looks to be a bug fix, can you please add Fixes: tag? > --- > drivers/misc/fastrpc.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c > index 05b2e7e4ad3b..c54c450cb571 100644 > --- a/drivers/misc/fastrpc.c > +++ b/drivers/misc/fastrpc.c > @@ -2663,6 +2663,7 @@ static void fastrpc_notify_users(struct fastrpc_user *user) > spin_lock(&user->lock); > list_for_each_entry(ctx, &user->pending, node) { > ctx->retval = -EPIPE; > + ctx->is_work_done = true; > complete(&ctx->work); > } > spin_unlock(&user->lock);