Messages in this thread | | | From | Kees Cook <> | Date | Wed, 1 Feb 2017 12:28:38 -0800 | Subject | Re: [PATCH v4 2nd 2/4] pstore: support multiple pmsg instances |
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On Mon, Jan 30, 2017 at 5:58 PM, Nobuhiro Iwamatsu <nobuhiro.iwamatsu.kw@hitachi.com> wrote: > From: Hiraku Toyooka <hiraku.toyooka.gu@hitachi.com> > > This enables pmsg to deal with multiple instances. One possible > use is content priority control on limited persistent store space. By > using different buffers, we can prevent important messages from being > overwritten by less important messages. > > When pstore backend module specifies the number of instances (num_pmsg) > in pstore_info, multiple /dev/pmsg[ID] appear. (ID is an integer > starting at 0. It corresponds to minor number of the each char device.) > Writes to each /dev/pmsg[ID] are isolated each other. After reboot, the > contents are available in /sys/fs/pstore/pmsg-[backend]-[ID]. > > Signed-off-by: Hiraku Toyooka <hiraku.toyooka.gu@hitachi.com> > Signed-off-by: Nobuhiro Iwamatsu <nobuhiro.iwamatsu.kw@hitachi.com> > Cc: Anton Vorontsov <anton@enomsg.org> > Cc: Colin Cross <ccross@android.com> > Cc: Kees Cook <keescook@chromium.org> > Cc: Mark Salyzyn <salyzyn@android.com> > Cc: Seiji Aguchi <seiji.aguchi.tr@hitachi.com> > Cc: Tony Luck <tony.luck@intel.com> > > V4: > Rebase. > V3: > rebase. > merged device_create(). > --- > fs/pstore/pmsg.c | 23 ++++++++++++++++------- > include/linux/pstore.h | 1 + > 2 files changed, 17 insertions(+), 7 deletions(-) > > diff --git a/fs/pstore/pmsg.c b/fs/pstore/pmsg.c > index 78f6176c020f..5da5cba4b387 100644 > --- a/fs/pstore/pmsg.c > +++ b/fs/pstore/pmsg.c > @@ -34,7 +34,8 @@ static ssize_t write_pmsg(struct file *file, const char __user *buf, > return -EFAULT; > > mutex_lock(&pmsg_lock); > - ret = psinfo->write_buf_user(PSTORE_TYPE_PMSG, 0, &id, 0, buf, 0, count, > + ret = psinfo->write_buf_user(PSTORE_TYPE_PMSG, 0, &id, > + iminor(file->f_inode), buf, 0, count, > psinfo); > mutex_unlock(&pmsg_lock); > return ret ? ret : count; > @@ -61,7 +62,7 @@ static char *pmsg_devnode(struct device *dev, umode_t *mode) > > void pstore_register_pmsg(void) > { > - struct device *pmsg_device; > + int i; > > pmsg_major = register_chrdev(0, PMSG_NAME, &pmsg_fops); > if (pmsg_major < 0) { > @@ -76,15 +77,23 @@ void pstore_register_pmsg(void) > } > pmsg_class->devnode = pmsg_devnode; > > - pmsg_device = device_create(pmsg_class, NULL, MKDEV(pmsg_major, 0), > - NULL, "%s%d", PMSG_NAME, 0); > - if (IS_ERR(pmsg_device)) { > - pr_err("failed to create device\n"); > - goto err_device; > + /* allocate additional /dev/pmsg[ID] */
This isn't "additional" any more, but rather "Allocate each pmsg device" or something.
> + for (i = 0; i < psinfo->num_pmsg; i++) { > + struct device *pmsg_device; > + > + pmsg_device = device_create(pmsg_class, NULL, > + MKDEV(pmsg_major, i), NULL, "%s%d", > + PMSG_NAME, i); > + if (IS_ERR(pmsg_device)) { > + pr_err("failed to create device\n"); > + goto err_device; > + } > } > return; > > err_device: > + for (i--; i >= 0; i--) > + device_destroy(pmsg_class, MKDEV(pmsg_major, i)); > class_destroy(pmsg_class); > err_class: > unregister_chrdev(pmsg_major, PMSG_NAME); > diff --git a/include/linux/pstore.h b/include/linux/pstore.h > index 0da29cae009b..7a5db4833b8a 100644 > --- a/include/linux/pstore.h > +++ b/include/linux/pstore.h > @@ -55,6 +55,7 @@ struct pstore_info { > size_t bufsize; > struct mutex read_mutex; /* serialize open/read/close */ > int flags; > + unsigned int num_pmsg;
Something in this patch needs to set num_pmsg to 1 unconditionally, so that bisectability is retained. I.e. after this patch, I should still get a /dev/pmsg0 device. Right now, it will be skipped since num_pmsg will always == 0.
> int (*open)(struct pstore_info *psi); > int (*close)(struct pstore_info *psi); > ssize_t (*read)(u64 *id, enum pstore_type_id *type, > -- > 2.11.0 >
Thanks for the rebasing!
-Kees
-- Kees Cook Pixel Security
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