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Wed, 26 Feb 2025 03:17:56 +0000 (GMT) Received: from epsmgmc1p1new.samsung.com (unknown [182.195.42.40]) by epsmtrp2.samsung.com (KnoxPortal) with ESMTP id 20250226031756epsmtrp2c1a292fe43e82fad3696e4df7bd64e3c~no8uqK6sH1292112921epsmtrp21; Wed, 26 Feb 2025 03:17:56 +0000 (GMT) X-AuditID: b6c32a43-99d9b2400000599a-52-67be87e47463 Received: from epsmtip2.samsung.com ( [182.195.34.31]) by epsmgmc1p1new.samsung.com (Symantec Messaging Gateway) with SMTP id A9.FA.23488.3E78EB76; Wed, 26 Feb 2025 12:17:56 +0900 (KST) Received: from tiffany (unknown [10.229.95.142]) by epsmtip2.samsung.com (KnoxPortal) with ESMTPA id 20250226031755epsmtip28f1ff721349e0bbaf40d1b156a9e4bd6~no8ufzFc60226702267epsmtip2l; Wed, 26 Feb 2025 03:17:55 +0000 (GMT) Date: Wed, 26 Feb 2025 12:16:28 +0900 From: Donghyeok Choe To: pmladek@suse.com Cc: linux-kernel@vger.kernel.org, john.ogness@linutronix.de, takakura@valinux.co.jp, youngmin.nam@samsung.com, hajun.sung@samsung.com, seungh.jung@samsung.com, jh1012.choi@samsung.com Subject: printk: selective deactivation of feature ignoring non panic cpu's messages Message-ID: <20250226031628.GB592457@tiffany> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFmphk+LIzCtJLcpLzFFi42LZdljTVPdJ+750g6m3JS2a9l9itng0fS2r xbYr8xktLu+aw2bx//FXVoujt56yW0za18hksfjAJ3YHDo93586xe/RtWcXosX7LVRaPT9Om sXt83iQXwBqVbZORmpiSWqSQmpecn5KZl26r5B0c7xxvamZgqGtoaWGupJCXmJtqq+TiE6Dr lpkDdIuSQlliTilQKCCxuFhJ386mKL+0JFUhI7+4xFYptSAlp8C8QK84Mbe4NC9dLy+1xMrQ wMDIFKgwITvj2b6b7AWtEhULvy5jamCcL9TFyMkhIWAi8WbyR9YuRi4OIYEdjBInprazQzif GCV63k9gB6kSEvjGKHHkbAZMR8vkeWwQRXsZJR5OX8QE4TxllJh6fiFYB4uAqsTElW/ZQGw2 AV2JSZ3bgGwODhEBEYlb6xRA6pkFdjNKtN7cwQRSIywQJvGzew0jiM0LVH/p8CQoW1Di5Mwn LBCbb7FLrL5gCWG7SHS+WcYKYQtLvDq+hR3ClpL4/G4v2HUSAs2MEpNuvGaCcGYwSlyZ/JkJ ospYYtazdrANzAKZEjuPL2EBuU5CQFniyC0WiDCfRMfhv+wQYV6JjjZoeKlInO97wAiza8Pc t1ATPSTmv9rHBAmtWIl3rycyT2CUnYXkhVlIlkHYOhILdn9imwW0gVlAWmL5Pw4IU1Ni/S79 BYysqxjFUguKc9NTk40KDOGRmpyfu4kRnBy1nHcwXpn/T+8QIxMH4yFGCQ5mJRFezsw96UK8 KYmVValF+fFFpTmpxYcYTYHxMZFZSjQ5H5ie80riDU0sDUzMzAzNjUwNzJXEeat3tKQLCaQn lqRmp6YWpBbB9DFxcEo1MDFty6r/lGy1SOnRh5C2P2eLfWKviXfws0i2fAq/kSAlaVllytNY pmuuet/2watNcTGtm6OSvC+dTLuxtbznRvrUhxunsv5g6Q1fmvmq+65xQF9iPquewYW1uvNX hYfyXYxcVTT94XGxd3Lnl6Sv918jZax5ocjqENNjUcXU0pfsqW9+PDD++iGL+yGDvuHLd3cn eyio3xK8ePX3NM1VPO03uZLk+2vsf9/SuFd75eup6S6KL7uunuy751tlVMNmaua/8DXvOaEq RW+B7XubqyLm71NI0N+/nWPuyxSvTQGljldjH2keV5uv+HXdqvvZp+xi+DY/dWb/EdhZsmfr 8yuX7HXOcb7o+u/6cv6GNCWW4oxEQy3mouJEAG2hnYEXBAAA X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFtrLLMWRmVeSWpSXmKPExsWy7bCSvO6T9n3pBp8uMFs07b/EbPFo+lpW i21X5jNaXN41h83i/+OvrBZHbz1lt5i0r5HJYvGBT+wOHB7vzp1j9+jbsorRY/2Wqywen6ZN Y/f4vEkugDWKyyYlNSezLLVI3y6BK2PS9d3sBYdEK5Yfymtg/MrfxcjJISFgItEyeR5bFyMX h5DAbkaJ/w8vM0IkpCTat8xkgrCFJe63HGGFKHrMKHHi8V5WkASLgKrExJVv2UBsNgFdiUmd 24BsDg4RARGJW+sUQOqZBfYySix4fYQZpEZYIEziZ/casAW8QPWXDk+CsgUlTs58wgJiMwto Sdz495IJZA6zgLTE8n8cExj5ZiGpmoWkahZC1QJG5lWMkqkFxbnpucmGBYZ5qeV6xYm5xaV5 6XrJ+bmbGMEhrKWxg/Hdtyb9Q4xMHIyHGCU4mJVEeDkz96QL8aYkVlalFuXHF5XmpBYfYpTm YFES511pGJEuJJCeWJKanZpakFoEk2Xi4JRqYGpQm7fVVlbI2VJe0KftSl/oPnuWmqnRJ9/P PfDj8wJLG7mLtSZ2arOtSlI7H+hLWJVJ1jrZqv+0jaqprbb8EMqyr8P7fEvV1zpFwQU/P4ap rfv1P+jrXYN6qSKnvT94JnItPKvoHZ7XsPOmWYmgQpnjEqbZ854dZZ/JycnBE/TuYcCK87ff lVkxqjzoO9Vqc413kaDLf997q/xN+j++9r/MEs3WX+mxd5fJuUjn6IxNB1sTjVdMzJNTkPs+ cWaE/y7X3muts4PubKw1vBD06/zkSNXzjGs/3MnfEnD3Wa29tljsssOe12qi8s8yacSlROnk phr3frVKv/ib+Wlb6tWr+z28nPZcS763a5apEktxRqKhFnNRcSIAVQfyRNACAAA= X-CMS-MailID: 20250226031756epcas2p3674cccc82687effb40575aa5fa2956e0 X-Msg-Generator: CA Content-Type: multipart/mixed; boundary="----7MjMDun-wBTKD0aJGk8MrTq1WBha5gge0B_F3lDBYtizvuhb=_147cc5_" X-Sendblock-Type: AUTO_CONFIDENTIAL CMS-TYPE: 102P DLP-Filter: Pass X-CFilter-Loop: Reflected X-CMS-RootMailID: 20250226031756epcas2p3674cccc82687effb40575aa5fa2956e0 References: ------7MjMDun-wBTKD0aJGk8MrTq1WBha5gge0B_F3lDBYtizvuhb=_147cc5_ Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline Hello. In 'Commit 779dbc2e78d7', a feature was included in which the message from non panic cpu was ignored. I understand that panic cpu's message is the most important feature in the SW livelockup issue. However, SOC vendor's linux kernel device driver developers in environments where hw reliability is not guaranteed The message from non panic cpu is also important. In the process of performing a panic when a specific cpu is fault, another cpu has the ability to output important err information through interrupt. If a particular cpu has an incorrect sfr access, the debugging device driver's ISR behavior to debug it helps you identify the problem easily. I can output non panic cpu's backtrace through Commit bcc954c6caba, but this seems to be not enough for me. I would like to print out the message of non panic cpu as it is. Can I use early_param to selectively disable that feature? For example, as below. I'm sending you an inquiry instead of a patch because I need to share more about my problem situation. Please forgive me if I broke the mailing etiquette. ex) diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index fb242739aec8..3f420e8bdb2c 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -2368,6 +2368,17 @@ void printk_legacy_allow_panic_sync(void) } } +static bool __read_mostly keep_printk_all_cpu_in_panic; + +static int __init keep_printk_all_cpu_in_panic_setup(char *str) +{ + keep_printk_all_cpu_in_panic = true; + pr_info("printk: keep printk all cpu in panic.\n"); + + return 0; +} +early_param("keep_printk_all_cpu_in_panic", keep_printk_all_cpu_in_panic_setup); + asmlinkage int vprintk_emit(int facility, int level, const struct dev_printk_info *dev_info, const char *fmt, va_list args) @@ -2379,13 +2390,15 @@ asmlinkage int vprintk_emit(int facility, int level, if (unlikely(suppress_printk)) return 0; - /* - * The messages on the panic CPU are the most important. If - * non-panic CPUs are generating any messages, they will be - * silently dropped. - */ - if (other_cpu_in_panic() && !panic_triggering_all_cpu_backtrace) - return 0; + if (!keep_printk_all_cpu_in_panic) { + /* + * The messages on the panic CPU are the most important. If + * non-panic CPUs are generating any messages, they will be + * silently dropped. + */ + if (other_cpu_in_panic() && !panic_triggering_all_cpu_backtrace) + return 0; + } Thank you. ------7MjMDun-wBTKD0aJGk8MrTq1WBha5gge0B_F3lDBYtizvuhb=_147cc5_ Content-Type: text/plain; charset="utf-8" ------7MjMDun-wBTKD0aJGk8MrTq1WBha5gge0B_F3lDBYtizvuhb=_147cc5_--