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Mon, 17 Mar 2025 05:08:32 +0000 (GMT) Received: from epsmgmcp1.samsung.com (unknown [182.195.42.82]) by epsmtrp1.samsung.com (KnoxPortal) with ESMTP id 20250317050832epsmtrp131749a3fe9baac09db07c47ff2468e11~tftuOc6Ps0499304993epsmtrp1C; Mon, 17 Mar 2025 05:08:32 +0000 (GMT) X-AuditID: b6c32a47-fd1c970000005659-91-67d7ae503e48 Received: from epsmtip1.samsung.com ( [182.195.34.30]) by epsmgmcp1.samsung.com (Symantec Messaging Gateway) with SMTP id BA.D1.33707.05EA7D76; Mon, 17 Mar 2025 14:08:32 +0900 (KST) Received: from tiffany (unknown [10.229.95.142]) by epsmtip1.samsung.com (KnoxPortal) with ESMTPA id 20250317050832epsmtip1780100868c82b12293720ec4052d223a~tftuBgTny2878228782epsmtip1a; Mon, 17 Mar 2025 05:08:32 +0000 (GMT) Date: Mon, 17 Mar 2025 14:06:57 +0900 From: Donghyeok Choe To: Petr Mladek Cc: linux-kernel@vger.kernel.org, rostedt@goodmis.org, john.ogness@linutronix.de, senozhatsky@chromium.org, takakura@valinux.co.jp, youngmin.nam@samsung.com, hajun.sung@samsung.com, seungh.jung@samsung.com, jh1012.choi@samsung.com, d7271.choe@samsung.com Subject: Re: printk: selective deactivation of feature ignoring non panic cpu's messages Message-ID: <20250317050657.GA693154@tiffany> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 In-Reply-To: X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFlrJJsWRmVeSWpSXmKPExsWy7bCmqW7AuuvpBj8/mlhc2zuR3aJp/yVm i0fT17JabLsyn9Hi8q45bBb/H39ltdjX8YDJYvfGRWwWR289ZbeYtK+RyWLxgU/sDtwesxsu sni07LvF7vHu3Dl2j74tqxg91m+5yuLxado0do/Pm+QC2KOybTJSE1NSixRS85LzUzLz0m2V vIPjneNNzQwMdQ0tLcyVFPISc1NtlVx8AnTdMnOAjlRSKEvMKQUKBSQWFyvp29kU5ZeWpCpk 5BeX2CqlFqTkFJgX6BUn5haX5qXr5aWWWBkaGBiZAhUmZGds2DyDteCfQMW9h2kNjPt5uxg5 OCQETCQWtFR2MXJxCAnsYJR41TGdsYuRE8j5xCjRc84TIgFktz74ywrT8GBzMkR8J6PEp9PX mCCcp4wSBz9tZwHpZhFQlWjqPAQ2iU1AV2JS5zY2EFtEQEni1fy7zCANzAItTBJXXnwGSwgL REnc+/qFFcTmBWpoO7iDCcIWlDg58wnYUE4BdYk3x3+AbZMQmMshce7Ca7BmCQEXiX2HvzBC 2MISr45vYYewpSRe9rexQzQ0M0pMuvEaqnsGo8SVyZ+ZIKqMJWY9awfrZhbIkLj08zoTxKPK EkdusUCE+SQ6Dv9lhwjzSnS0CUF0qkic73vACLNrw9y3UBM9JOa/2gcNlqtMEv3LZ7FMYJSb heShWUi2Qdg6Egt2f2KbBbSCWUBaYvk/DghTU2L9Lv0FjKyrGMVSC4pz01OLjQqM4RGcnJ+7 iRGcZrXcdzDOePtB7xAjEwfjIUYJDmYlEd7+RdfThXhTEiurUovy44tKc1KLDzGaAqNnIrOU aHI+MNHnlcQbmlgamJiZGZobmRqYK4nzVu9oSRcSSE8sSc1OTS1ILYLpY+LglGpg6pKz0rrr eqB85utzy/X2HNn0K/2b3wvvdg6vpXP5C/6uFeYqLdLRltKYmlAgKhV0f13s94KbhzO2mcpt 75gdWbSnrHjpBM1Fbr4NtxomeFQnfTEOcWzVKRAUDtH6vVSRb8buadkrth+9N33n5XdMytPT S7QYbmddyPy10Uba8Zjsxzd/1QRjOV6LnSlq0jWK0NK9dcR1m/Wn90wSBYLR/3IrApzNBbR4 v1tyfpJcffG/sq6C94XSdOErF3e/n3e/bPa/eU0H0n5uPye2XNbx/HltxvDlhowPy6Kqokzk pX+t8PC/Y3SGxafYyq9RYfkpx41SZ3m5Z2haWIsfVZS6e2Lu7jnPQ7XYe39FNwcrsRRnJBpq MRcVJwIASfxJOjwEAAA= X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFnrDLMWRmVeSWpSXmKPExsWy7bCSnG7AuuvpBnPP8Vpc2zuR3aJp/yVm i0fT17JabLsyn9Hi8q45bBb/H39ltdjX8YDJYvfGRWwWR289ZbeYtK+RyWLxgU/sDtwesxsu sni07LvF7vHu3Dl2j74tqxg91m+5yuLxado0do/Pm+QC2KO4bFJSczLLUov07RK4Mp6d7mYv 2MdX0XH9F3MD4wzuLkYODgkBE4kHm5O7GLk4hAS2M0osmvyKrYuREyguJdG+ZSYThC0scb/l CCtE0WNGidd7m9lBEiwCqhJNnYcYQWw2AV2JSZ3bwJpFBJQkXs2/ywzSwCzQxiRxfOZNVpCE sECUxL2vX8BsXqCGtoM7mCCm3maSmPqxkQkiIShxcuYTFhCbWUBL4sa/l0wgpzILSEss/8cB EuYUUJd4c/wH0wRGgVlIOmYh6ZiF0LGAkXkVo2hqQXFuem5ygaFecWJucWleul5yfu4mRnCE aAXtYFy2/q/eIUYmDsZDjBIczEoivP2LrqcL8aYkVlalFuXHF5XmpBYfYpTmYFES51XO6UwR EkhPLEnNTk0tSC2CyTJxcEo1MPX0rcr2O6y2uKN0uWqFiLXkJJG1rnnrb/F48q/7JKF0Zhqb g/7RTzEx6XNY3Zceqs/YOPFl0P9HHadvR0hOyF+T/Mrov+5PHaHcU9IL98q9WnvMZlZG9/I9 TfxL6uRKzWdNOvnwlu7FUzZbetzzGIset/xg2jb9ZUtXZWTHzWK5g39aD5y//doxPKV/4+E1 HIfT6/fm1rK7Lzyi/YPpj4mqtY/Wdt2JRqmX8mZsLygJXXGnIGtr8/SJId93/zvsrnJFJ6Go veOzQm6k94qy32cda3dMObrcuE3PZ97P0zrVhTcjy5x/h/UpWm2cL/vzMLvqw+AdCyfUFQh9 vKf76sC2ORMieoKXtR6YJ2W/O0+JpTgj0VCLuag4EQAtoZta/wIAAA== X-CMS-MailID: 20250317050832epcas2p4767823247bba56b2cd36571bc2963582 X-Msg-Generator: CA Content-Type: multipart/mixed; boundary="----K-Xcka4Xsim0K0-JuHAa3VmVr3oPR9my9iMvsSsU8QXUQUBj=_22279_" X-Sendblock-Type: AUTO_CONFIDENTIAL CMS-TYPE: 102P DLP-Filter: Pass X-CFilter-Loop: Reflected X-CMS-RootMailID: 20250226031756epcas2p3674cccc82687effb40575aa5fa2956e0 References: <20250226031628.GB592457@tiffany> <84ikoxxrfy.fsf@jogness.linutronix.de> <8434fytakt.fsf@jogness.linutronix.de> <84ikoorj53.fsf@jogness.linutronix.de> ------K-Xcka4Xsim0K0-JuHAa3VmVr3oPR9my9iMvsSsU8QXUQUBj=_22279_ Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline On Tue, Mar 04, 2025 at 03:15:46PM +0100, Petr Mladek wrote: > On Tue 2025-03-04 15:05:52, John Ogness wrote: > > On 2025-03-04, Petr Mladek wrote: > > > I mean something like: > > > > > > --- a/kernel/printk/printk_ringbuffer.c > > > +++ b/kernel/printk/printk_ringbuffer.c > > > @@ -2143,7 +2143,9 @@ static bool _prb_read_valid(struct printk_ringbuffer *rb, u64 *seq, > > > * But it would have the sequence number returned > > > * by "prb_next_reserve_seq() - 1". > > > */ > > > - if (this_cpu_in_panic() && ((*seq + 1) < prb_next_reserve_seq(rb))) > > > + if (this_cpu_in_panic() && > > > + (!printk_debug_non_panic_cpus || legacy_allow_panic_sync) && > > > + ((*seq + 1) < prb_next_reserve_seq(rb))) > > > (*seq)++; > > > else > > > return false; > > > > Ah, OK. Thanks for the clarification > > > > > OK, I propose the following changes: > > > > > > + rename the option to "printk_debug_non_panic_cpus" > > > > > > + do not skip the messages in _prb_read_valid() when this option > > > is used before the non-panic CPUs are stopped. > > > > And of course: > > > > + allow non-panic CPUs in panic to store messages when this option > > is set > > I would also keep the dump_stack_lvl() implementation as it is, even if > > it could lead to interweaving of backtraces. Anyone using > > printk_debug_non_panic_cpus should have CONFIG_PRINTK_CALLER enabled. Hi Petr Mladek, This is gentle remind. I did upload the patch containing the above contents. Link: https://lore.kernel.org/all/20250305044046.1249972-1-d7271.choe@samsung.com/ Even if it's not necessarily this patch, I hope the content will be applied. When can the 'printk_debug_non_panic_cpus' function be reflected in mainline source code? Thanks. ------K-Xcka4Xsim0K0-JuHAa3VmVr3oPR9my9iMvsSsU8QXUQUBj=_22279_ Content-Type: text/plain; charset="utf-8" ------K-Xcka4Xsim0K0-JuHAa3VmVr3oPR9my9iMvsSsU8QXUQUBj=_22279_--