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[73.69.118.222]) by smtp.gmail.com with ESMTPSA id d23sm5156894qkj.26.2020.05.02.07.35.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 02 May 2020 07:35:59 -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 v1 1/3] printk: honor the max_reason field in kmsg_dumper Date: Sat, 2 May 2020 10:35:53 -0400 Message-Id: <20200502143555.543636-2-pasha.tatashin@soleen.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200502143555.543636-1-pasha.tatashin@soleen.com> References: <20200502143555.543636-1-pasha.tatashin@soleen.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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 | 16 +++++++++------- 2 files changed, 10 insertions(+), 7 deletions(-) diff --git a/include/linux/kmsg_dump.h b/include/linux/kmsg_dump.h index 2e7a1e032c71..c0d703b7ce38 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 = KMSG_DUMP_POWEROFF }; /** diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index 9a9b6156270b..04c1e9a9b139 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -3085,6 +3085,8 @@ EXPORT_SYMBOL(printk_timed_ratelimit); static DEFINE_SPINLOCK(dump_list_lock); static LIST_HEAD(dump_list); +static bool always_kmsg_dump; +module_param_named(always_kmsg_dump, always_kmsg_dump, bool, S_IRUGO | S_IWUSR); /** * kmsg_dump_register - register a kernel log dumper. @@ -3106,6 +3108,12 @@ int kmsg_dump_register(struct kmsg_dumper *dumper) spin_lock_irqsave(&dump_list_lock, flags); /* Don't allow registering multiple times */ if (!dumper->registered) { + if (!dumper->max_reason) { + if (always_kmsg_dump) + dumper->max_reason = KMSG_DUMP_MAX; + else + dumper->max_reason = KMSG_DUMP_OOPS; + } dumper->registered = 1; list_add_tail_rcu(&dumper->list, &dump_list); err = 0; @@ -3141,9 +3149,6 @@ int kmsg_dump_unregister(struct kmsg_dumper *dumper) } EXPORT_SYMBOL_GPL(kmsg_dump_unregister); -static bool always_kmsg_dump; -module_param_named(always_kmsg_dump, always_kmsg_dump, bool, S_IRUGO | S_IWUSR); - /** * kmsg_dump - dump kernel log to kernel message dumpers. * @reason: the reason (oops, panic etc) for dumping @@ -3157,12 +3162,9 @@ 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) + if (reason > dumper->max_reason) continue; /* initialize iterator with data about the stored records */ -- 2.25.1