Hi, Thanks for your review.
> -----Original Message----- > From: keesc...@google.com [mailto:keesc...@google.com] On Behalf Of Kees > Cook > Sent: Thursday, February 02, 2017 5:29 AM > To: 岩松信洋 / IWAMATSU，NOBUHIRO > Cc: Anton Vorontsov; Colin Cross; Tony Luck; LKML; Hiraku Toyooka; Mark > Salyzyn; 阿口誠司 / AGUCHI，SEIJI > Subject: Re: [PATCH v4 2nd 2/4] pstore: support multiple pmsg instances > > On Mon, Jan 30, 2017 at 5:58 PM, Nobuhiro Iwamatsu > <nobuhiro.iwamatsu...@hitachi.com> wrote: > > From: Hiraku Toyooka <hiraku.toyooka...@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...@hitachi.com> > > Signed-off-by: Nobuhiro Iwamatsu <nobuhiro.iwamatsu...@hitachi.com> > > Cc: Anton Vorontsov <an...@enomsg.org> > > Cc: Colin Cross <ccr...@android.com> > > Cc: Kees Cook <keesc...@chromium.org> > > Cc: Mark Salyzyn <saly...@android.com> > > Cc: Seiji Aguchi <seiji.aguchi...@hitachi.com> > > Cc: Tony Luck <tony.l...@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. OK, I will fix. > > > + 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. Indeed, I will fix too. Best regards, Nobuhiro
