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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id s44sm3065952pjc.28.2020.05.05.14.59.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 05 May 2020 14:59:38 -0700 (PDT) Date: Tue, 5 May 2020 14:59:37 -0700 From: Kees Cook To: Pavel Tatashin Cc: jmorris@namei.org, sashal@kernel.org, linux-kernel@vger.kernel.org, pmladek@suse.com, sergey.senozhatsky@gmail.com, rostedt@goodmis.org, anton@enomsg.org, ccross@android.com, tony.luck@intel.com, robh+dt@kernel.org, devicetree@vger.kernel.org Subject: Re: [PATCH v2 2/5] pstore/platform: pass max_reason to kmesg dump Message-ID: <202005051444.14B6686@keescook> References: <20200505154510.93506-1-pasha.tatashin@soleen.com> <20200505154510.93506-3-pasha.tatashin@soleen.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200505154510.93506-3-pasha.tatashin@soleen.com> Sender: devicetree-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On Tue, May 05, 2020 at 11:45:07AM -0400, Pavel Tatashin wrote: > Add a new field to pstore_info that passes information about kmesg dump > maximum reason. > > This allows a finer control of what kmesg dumps are stored on pstore > device. > > Those clients that do not explicitly set this field (keep it equal to 0), > get the default behavior: dump only Oops and Panics, and dump everything > if printk.always_kmsg_dump is provided. > > Signed-off-by: Pavel Tatashin > --- > fs/pstore/platform.c | 4 +++- > include/linux/pstore.h | 3 +++ > 2 files changed, 6 insertions(+), 1 deletion(-) > > diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c > index 408277ee3cdb..75bf8a43f92a 100644 > --- a/fs/pstore/platform.c > +++ b/fs/pstore/platform.c > @@ -602,8 +602,10 @@ int pstore_register(struct pstore_info *psi) > if (pstore_is_mounted()) > pstore_get_records(0); > > - if (psi->flags & PSTORE_FLAGS_DMESG) > + if (psi->flags & PSTORE_FLAGS_DMESG) { > + pstore_dumper.max_reason = psinfo->max_reason; > pstore_register_kmsg(); > + } I haven't finished reading the whole series carefully, but I think something we can do here to make things a bit more user-friendly is to do the KMSG_DUMP_UNDEF value here to get us the "all" instead of INT_MAX: if (psi->flags & PSTORE_FLAGS_DMESG) { pstore_dumper.max_reason = psinfo->max_reason; if (pstore_dumper.max_reason == KMSG_DUMP_UNDEF) pstore_dumper.max_reason = KMSG_DUMP_MAX; pstore_register_kmsg(); } That way setting max_reason to 0 without setting dump_oops at all will get "all". I think it'll need some tweaks to the next patch. > if (psi->flags & PSTORE_FLAGS_CONSOLE) > pstore_register_console(); > if (psi->flags & PSTORE_FLAGS_FTRACE) > diff --git a/include/linux/pstore.h b/include/linux/pstore.h > index e779441e6d26..45ae424bfeb5 100644 > --- a/include/linux/pstore.h > +++ b/include/linux/pstore.h > @@ -97,6 +97,8 @@ struct pstore_record { > * @read_mutex: serializes @open, @read, @close, and @erase callbacks > * @flags: bitfield of frontends the backend can accept writes for > * @data: backend-private pointer passed back during callbacks > + * @max_reason: Used when PSTORE_FLAGS_DMESG is set. Contains the > + * kmsg_dump_reason enum value. Nit: please move this above @data since it has a @flags dependency. > * > * Callbacks: > * > @@ -180,6 +182,7 @@ struct pstore_info { > > int flags; > void *data; > + int max_reason; > > int (*open)(struct pstore_info *psi); > int (*close)(struct pstore_info *psi); > -- > 2.25.1 > Looking good! -- Kees Cook