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[73.69.118.222]) by smtp.gmail.com with ESMTPSA id x7sm2122407qkx.36.2020.05.05.08.45.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 05 May 2020 08:45:13 -0700 (PDT) From: Pavel Tatashin To: pasha.tatashin@soleen.com, jmorris@namei.org, sashal@kernel.org, linux-kernel@vger.kernel.org, pmladek@suse.com, sergey.senozhatsky@gmail.com, rostedt@goodmis.org, keescook@chromium.org, anton@enomsg.org, ccross@android.com, tony.luck@intel.com, robh+dt@kernel.org, devicetree@vger.kernel.org Subject: [PATCH v2 1/5] printk: honor the max_reason field in kmsg_dumper Date: Tue, 5 May 2020 11:45:06 -0400 Message-Id: <20200505154510.93506-2-pasha.tatashin@soleen.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200505154510.93506-1-pasha.tatashin@soleen.com> References: <20200505154510.93506-1-pasha.tatashin@soleen.com> MIME-Version: 1.0 Sender: devicetree-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org kmsg_dump() allows to dump kmesg buffer for various system events: oops, panic, reboot, etc. It provides an interface to register a callback call for clients, and in that callback interface there is a field "max_reason" which gets ignored unless always_kmsg_dump is passed as kernel parameter. Allow clients to decide max_reason, and keep the current behavior when max_reason is not set. Signed-off-by: Pavel Tatashin --- include/linux/kmsg_dump.h | 1 + kernel/printk/printk.c | 15 +++++++++++---- 2 files changed, 12 insertions(+), 4 deletions(-) diff --git a/include/linux/kmsg_dump.h b/include/linux/kmsg_dump.h index 2e7a1e032c71..cfc042066be7 100644 --- a/include/linux/kmsg_dump.h +++ b/include/linux/kmsg_dump.h @@ -28,6 +28,7 @@ enum kmsg_dump_reason { KMSG_DUMP_RESTART, KMSG_DUMP_HALT, KMSG_DUMP_POWEROFF, + KMSG_DUMP_MAX }; /** diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index 9a9b6156270b..1aab69a8a2bf 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -3157,12 +3157,19 @@ void kmsg_dump(enum kmsg_dump_reason reason) struct kmsg_dumper *dumper; unsigned long flags; - if ((reason > KMSG_DUMP_OOPS) && !always_kmsg_dump) - return; - rcu_read_lock(); list_for_each_entry_rcu(dumper, &dump_list, list) { - if (dumper->max_reason && reason > dumper->max_reason) + enum kmsg_dump_reason cur_reason = dumper->max_reason; + + /* + * If client has not provided a specific max_reason, default + * to KMSG_DUMP_OOPS, unless always_kmsg_dump was set. + */ + if (cur_reason == KMSG_DUMP_UNDEF) { + cur_reason = always_kmsg_dump ? KMSG_DUMP_MAX : + KMSG_DUMP_OOPS; + } + if (reason > cur_reason) continue; /* initialize iterator with data about the stored records */