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Thu, 17 Feb 2022 21:52:01 -0800 (PST) Date: Thu, 17 Feb 2022 21:54:08 -0800 From: Bjorn Andersson To: Kishon Vijay Abraham I Subject: Re: [PATCH v5 1/2] remoteproc: Introduce sysfs_read_only flag Message-ID: References: <20220216081224.9956-1-p-mohan@ti.com> <20220216081224.9956-2-p-mohan@ti.com> <0d44d73f-d882-83db-9cf2-09f7cdc91ab2@ti.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <0d44d73f-d882-83db-9cf2-09f7cdc91ab2@ti.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220217_215205_564134_81EDF63A X-CRM114-Status: GOOD ( 35.34 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: vigneshr@ti.com, mathieu.poirier@linaro.org, linux-remoteproc@vger.kernel.org, linux-kernel@vger.kernel.org, Puranjay Mohan , linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu 17 Feb 21:00 PST 2022, Kishon Vijay Abraham I wrote: > > > On 16/02/22 1:42 pm, Puranjay Mohan wrote: > > The remoteproc framework provides sysfs interfaces for changing > > the firmware name and for starting/stopping a remote processor > > through the sysfs files 'state' and 'firmware'. The 'coredump' > > file is used to set the coredump configuration. The 'recovery' > > sysfs file can also be used similarly to control the error recovery > > state machine of a remoteproc. These interfaces are currently > > allowed irrespective of how the remoteprocs were booted (like > > remoteproc self auto-boot, remoteproc client-driven boot etc). > > These interfaces can adversely affect a remoteproc and its clients > > especially when a remoteproc is being controlled by a remoteproc > > client driver(s). Also, not all remoteproc drivers may want to > > support the sysfs interfaces by default. > > > > Add support to make the remoteproc sysfs files read only by > > introducing a state flag 'sysfs_read_only' that the individual > > remoteproc drivers can set based on their usage needs. The default > > behavior is to allow the sysfs operations as before. > > > > Implement attribute_group->is_visible() to make the sysfs > > entries read only when 'sysfs_read_only' flag is set. > > > > Signed-off-by: Puranjay Mohan > > Reviewed-by: Mathieu Poirier > > --- > > Changes in v4->v5: > > Rename deny_sysfs_ops to sysfs_read_only. > > Make coredump readonly with other files. > > > > Changes in v3->v4: > > Use mode = 0444 in rproc_is_visible() to make the sysfs entries > > read-only when the deny_sysfs_ops flag is set. > > --- > > drivers/remoteproc/remoteproc_sysfs.c | 19 ++++++++++++++++++- > > include/linux/remoteproc.h | 2 ++ > > 2 files changed, 20 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/remoteproc/remoteproc_sysfs.c b/drivers/remoteproc/remoteproc_sysfs.c > > index ea8b89f97d7b..abf0cd05d5e1 100644 > > --- a/drivers/remoteproc/remoteproc_sysfs.c > > +++ b/drivers/remoteproc/remoteproc_sysfs.c > > @@ -230,6 +230,22 @@ static ssize_t name_show(struct device *dev, struct device_attribute *attr, > > } > > static DEVICE_ATTR_RO(name); > > > > +static umode_t rproc_is_visible(struct kobject *kobj, struct attribute *attr, > > + int n) > > +{ > > + struct device *dev = kobj_to_dev(kobj); > > + struct rproc *rproc = to_rproc(dev); > > + umode_t mode = attr->mode; > > + > > + if (rproc->sysfs_read_only && (attr == &dev_attr_recovery.attr || > > + attr == &dev_attr_firmware.attr || > > + attr == &dev_attr_state.attr || > > + attr == &dev_attr_coredump.attr)) > > + mode = 0444; > > Nitpick: use S_IRUGO instead of 0444. > Thanks for the suggestion Kishon, but I like 0444, it has direct meaning to me. So unless there's some directive to use S_I*** throughout the kernel I would prefer this. Regards, Bjorn > Thanks, > Kishon > > + > > + return mode; > > +} > > + > > static struct attribute *rproc_attrs[] = { > > &dev_attr_coredump.attr, > > &dev_attr_recovery.attr, > > @@ -240,7 +256,8 @@ static struct attribute *rproc_attrs[] = { > > }; > > > > static const struct attribute_group rproc_devgroup = { > > - .attrs = rproc_attrs > > + .attrs = rproc_attrs, > > + .is_visible = rproc_is_visible, > > }; > > > > static const struct attribute_group *rproc_devgroups[] = { > > diff --git a/include/linux/remoteproc.h b/include/linux/remoteproc.h > > index e0600e1e5c17..93a1d0050fbc 100644 > > --- a/include/linux/remoteproc.h > > +++ b/include/linux/remoteproc.h > > @@ -523,6 +523,7 @@ struct rproc_dump_segment { > > * @table_sz: size of @cached_table > > * @has_iommu: flag to indicate if remote processor is behind an MMU > > * @auto_boot: flag to indicate if remote processor should be auto-started > > + * @sysfs_read_only: flag to make remoteproc sysfs files read only > > * @dump_segments: list of segments in the firmware > > * @nb_vdev: number of vdev currently handled by rproc > > * @elf_class: firmware ELF class > > @@ -562,6 +563,7 @@ struct rproc { > > size_t table_sz; > > bool has_iommu; > > bool auto_boot; > > + bool sysfs_read_only; > > struct list_head dump_segments; > > int nb_vdev; > > u8 elf_class; > > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel