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[103.229.16.4]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-8396563f11csm27141591b3a.3.2026.05.11.17.55.01 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 11 May 2026 17:55:03 -0700 (PDT) Message-ID: Date: Tue, 12 May 2026 08:54:59 +0800 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 v3] coresight: fix missing error code when trace ID is invalid To: Leo Yan Cc: Richard Cheng , Suzuki K Poulose , Mike Leach , James Clark , Alexander Shishkin , Tingwei Zhang , coresight@lists.linaro.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org References: <20260511-fix-trace-id-error-v3-1-ac4c8356efff@oss.qualcomm.com> <146d34e9-caa3-4119-a3f3-79515b3f2c46@oss.qualcomm.com> <20260511144556.GA34802@e132581.arm.com> Content-Language: en-US From: Jie Gan In-Reply-To: <20260511144556.GA34802@e132581.arm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNTEyMDAwNCBTYWx0ZWRfX4W2+qsjToppa IpAC3pd0lasGFD1n3BGrI1MN6HN3zMuZTEOQ/n3INg0tbNvXuRjsMCgqN/d9ZjnlrYaG5EFioYu MdrpyBbe3EAvpbBp3vBKBoMggXOPvoIZKmal1+ghubyMOcf7e7VwzLT5qD+lB5gLLidCNgu8M3E +PSt3eADywPv47I38ppd5qOa5nTl3b9sS2dIlr4OZpXkypL+0bi7AYv5edFfSHVULHYIJ5lB8hF zFfBxmPChnHJl25b/AOv4f8mAUf/EcY7SkfuSeo5eN4eFlaB1w0znZ8+Z2iWs789wG4jhQs9n5S 4WzSOzmf1LRELTGm3e6WFQbgul/ox/VihYDSbwLJ+86Un4BraqHoXd2toDHkOdoh+Hjrmc30sP9 sGY/NjPz8t2cvyY3IVHJlTPyfMG4zy23UiSfQ/uuEQ41QfsWlveDLOOsV6V9WXn3bP4P9ZtMFyF 2WEwf1sgZLYqQqIrC2Q== X-Proofpoint-GUID: WfFUcQr8LWvKYqPyzIPeQ4rI9gxG8WDu X-Proofpoint-ORIG-GUID: WfFUcQr8LWvKYqPyzIPeQ4rI9gxG8WDu X-Authority-Analysis: v=2.4 cv=Y5XIdBeN c=1 sm=1 tr=0 ts=6a027a69 cx=c_pps a=rEQLjTOiSrHUhVqRoksmgQ==:117 a=nuhDOHQX5FNHPW3J6Bj6AA==:17 a=IkcTkHD0fZMA:10 a=NGcC8JguVDcA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=eoimf2acIAo5FJnRuUoq:22 a=azZi9I3KAAAA:8 a=nZrqWMUQ7_P3nV2vYQYA:9 a=QEXdDO2ut3YA:10 a=2VI0MkxyNR6bbpdq8BZq:22 a=9agbdnaLCrZLQcVvdjT-:22 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-05-11_05,2026-05-08_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 malwarescore=0 lowpriorityscore=0 impostorscore=0 suspectscore=0 adultscore=0 phishscore=0 priorityscore=1501 clxscore=1015 bulkscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2605050000 definitions=main-2605120004 On 5/11/2026 10:45 PM, Leo Yan wrote: > On Mon, May 11, 2026 at 05:27:10PM +0800, Jie Gan wrote: > > [...] > >>>> @@ -755,10 +755,16 @@ void coresight_path_assign_trace_id(struct coresight_path *path, >>>> * Non 0 is either success or fail. >>>> */ >>>> if (trace_id != 0) { >>>> - path->trace_id = trace_id; >>>> - return; >>>> + if (IS_VALID_CS_TRACE_ID(trace_id)) { >>>> + path->trace_id = trace_id; >>>> + return 0; >>>> + } >>>> + >>>> + return -EINVAL; > > I'd advocate a bit early exit style, like: > > /* 0 means the device has no ID assignment, so keep searching */ > if (trace_id == 0) > continue; > > if (!IS_VALID_CS_TRACE_ID(trace_id)) > return -EINVAL; > > path->trace_id = trace_id; > return 0; > > Early exit can reduce indentation depth, and it handles simple cases > first and then the complex logic. In some cases (maye not this case), > we may benefit a bit from compiler optimization [1]. > Thanks, that's a good suggestion and much simpler than my solution. > [1] https://xania.org/202512/18-partial-inlining > > [...] > >> The return value has been ignored in perf mode. It will introduce noisy by >> adding __must_check. So I think its better without __must_check? > > Wouldn't it need to update perf mode as well? I will also update the perf mode for consistent usage. Thanks, Jie > > Regarding __must_check, I searched Documentation but didn't find > guidance on when it should be used. I don't want to use this annotation > randomly (some functions use it and some not), this will be hard for > everyone to follow up. > > IMO, it's fine not to use __must_check here. I would leave this to > Suzuki and other maintainers if have different opinions. > > Thanks, > Leo