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Thu, 28 Aug 2025 21:39:29 -0700 (PDT) Received: from [127.0.0.1] ([103.88.46.62]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-7722a26a4e5sm1070875b3a.19.2025.08.28.21.39.16 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 28 Aug 2025 21:39:29 -0700 (PDT) Message-ID: <58e87116-a8af-4c8f-b5b4-3d0540cd3333@gmail.com> Date: Fri, 29 Aug 2025 12:39:14 +0800 Precedence: bulk X-Mailing-List: linux-fbdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 3/9] crash_core: use panic_try_start() in crash_kexec() To: Qianqiang Liu Cc: Andrew Morton , Baoquan He , Yury Norov , Simona Vetter , Helge Deller , Petr Mladek , Steven Rostedt , John Ogness , Sergey Senozhatsky , Vivek Goyal , Dave Young , Kees Cook , Tony Luck , "Guilherme G. Piccoli" , Thomas Zimmermann , =?UTF-8?B?VmlsbGUgU3lyasOkbMOk?= , Shixiong Ou , Zsolt Kajtar , Ingo Molnar , Nam Cao , Jonathan Cameron , Joel Fernandes , Joel Granados , Jason Gunthorpe , Sohil Mehta , Feng Tang , Sravan Kumar Gundu , Douglas Anderson , Thomas Gleixner , Anna Schumaker , "Darrick J. Wong" , Max Kellermann , Yunhui Cui , Tejun Heo , Luo Gengkun , Li Huafei , Thorsten Blum , Yicong Yang , linux-fbdev@vger.kernel.org, dri-devel@lists.freedesktop.org, kexec@lists.infradead.org, linux-hardening@vger.kernel.org, linux-kernel@vger.kernel.org References: <20250825022947.1596226-1-wangjinchao600@gmail.com> <20250825022947.1596226-4-wangjinchao600@gmail.com> Content-Language: en-US From: Jinchao Wang In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 8/29/25 10:30, Qianqiang Liu wrote: > On Mon, Aug 25, 2025 at 10:29:31AM +0800, Jinchao Wang wrote: >> crash_kexec() had its own code to exclude parallel execution by setting >> panic_cpu. This is already handled by panic_try_start(). Switch to >> panic_try_start() to remove the duplication and keep the logic consistent. >> >> Signed-off-by: Jinchao Wang >> --- >> kernel/crash_core.c | 15 +++------------ >> 1 file changed, 3 insertions(+), 12 deletions(-) >> >> diff --git a/kernel/crash_core.c b/kernel/crash_core.c >> index a4ef79591eb2..bb38bbaf3a26 100644 >> --- a/kernel/crash_core.c >> +++ b/kernel/crash_core.c >> @@ -4,6 +4,7 @@ >> * Copyright (C) 2002-2004 Eric Biederman >> */ >> >> +#include "linux/panic.h" > > Can you change this line of code to #include ? Yes, I will. Thanks for the feedback.> >> #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt >> >> #include >> @@ -143,17 +144,7 @@ STACK_FRAME_NON_STANDARD(__crash_kexec); >> >> __bpf_kfunc void crash_kexec(struct pt_regs *regs) >> { >> - int old_cpu, this_cpu; >> - >> - /* >> - * Only one CPU is allowed to execute the crash_kexec() code as with >> - * panic(). Otherwise parallel calls of panic() and crash_kexec() >> - * may stop each other. To exclude them, we use panic_cpu here too. >> - */ >> - old_cpu = PANIC_CPU_INVALID; >> - this_cpu = raw_smp_processor_id(); >> - >> - if (atomic_try_cmpxchg(&panic_cpu, &old_cpu, this_cpu)) { >> + if (panic_try_start()) { >> /* This is the 1st CPU which comes here, so go ahead. */ >> __crash_kexec(regs); >> >> @@ -161,7 +152,7 @@ __bpf_kfunc void crash_kexec(struct pt_regs *regs) >> * Reset panic_cpu to allow another panic()/crash_kexec() >> * call. >> */ >> - atomic_set(&panic_cpu, PANIC_CPU_INVALID); >> + panic_reset(); >> } >> } >> >> -- >> 2.43.0 > -- Best regards, Jinchao