[PATCH v3 RFT 0/2] PM / Hibernate: sysfs resume

[PATCH v3 RFT 0/2] PM / Hibernate: sysfs resume

[Sebastian Capella]

Patchset related to hibernation resume: one enhancement to make the use
of an existing resume file more general and one enhances name_to_dev_t
to ignore the trailing newlines coming from userspace.

Both patches are based on the 3.11 tag.  This was tested on a
Pandaboard with partial hibernation support, and compiled for x86.

Further testing is needed on other platforms.  Please let me know if
you're able to verify this on any other systems.

[PATCH 1/2] init/do_mounts.c: ignore final \n in name_to_dev_t
  init/do_mounts.c |   23 ++++++++++++++++++-----
  1 file changed, 18 insertions(+), 5 deletions(-)

  Changes name_to_dev_t to handle a trailing newline in the
  input buffer, which will allow name_to_dev_t to be used
  directly with user buffers without requiring a copy.
  Also adds a const to the name parameter which reflects
  how name_to_dev_t is treating the input buffer currently.
  This also allows direct use of user buffers
  (from resume_store for example).

[PATCH 2/2] PM / Hibernate: use name_to_dev_t to parse resume
  kernel/power/hibernate.c |   15 ++++-----------
  1 file changed, 4 insertions(+), 11 deletions(-)

  Use name_to_dev_t to parse the /sys/power/resume file making the
  syntax more flexible.  It supports the previous use syntax
  and additionally can support other formats such as
  /dev/devicenode and UUID= formats.

  By changing /sys/debug/resume to accept the same syntax as
  the resume=device parameter, we can parse the resume=device
  in the initrd init script and use the resume device directly
  from the kernel command line.

Changes in v3:
--------------
* Dropped documentation patch as it went in through trivial
* Added patch for name_to_dev_t to support directly parsing userspace
  buffer

Changes in v2:
--------------
* Added check for null return of kstrndup in hibernate.c


Thanks,

Sebastian

[PATCH v3 RFT 1/2] init/do_mounts.c: ignore final \n in name_to_dev_t

[Sebastian Capella]

Enhance name_to_dev_t to handle trailing newline characters
on device paths.  Some inputs to name_to_dev_t may come from
userspace where oftentimes a '\n' is appended to the path.
Added const to the name buffer in both the function
declaration and the prototype to reflect input buffer
handling.

By handling trailing newlines in name_to_dev_t, userspace
buffers may be directly passed to name_to_dev_t without
modification.

Signed-off-by: Sebastian Capella <sebastian.capella@linaro.org>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Serge Hallyn <serge.hallyn@canonical.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Stephen Warren <swarren@nvidia.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
---
 include/linux/mount.h |    2 +-
 init/do_mounts.c      |   25 +++++++++++++++++++------
 2 files changed, 20 insertions(+), 7 deletions(-)

diff --git a/include/linux/mount.h b/include/linux/mount.h
index 73005f9..b024d5c 100644
--- a/include/linux/mount.h
+++ b/include/linux/mount.h
@@ -76,6 +76,6 @@ extern struct vfsmount *vfs_kern_mount(struct file_system_type *type,
 extern void mnt_set_expiry(struct vfsmount *mnt, struct list_head *expiry_list);
 extern void mark_mounts_for_expiry(struct list_head *mounts);
 
-extern dev_t name_to_dev_t(char *name);
+extern dev_t name_to_dev_t(const char *name);
 
 #endif /* _LINUX_MOUNT_H */
diff --git a/init/do_mounts.c b/init/do_mounts.c
index 816014c..5a031de 100644
--- a/init/do_mounts.c
+++ b/init/do_mounts.c
@@ -143,6 +143,13 @@ static dev_t devt_from_partuuid(const char *uuid_str)
 		clear_root_wait = true;
 		goto done;
 	}
+	if (uuid_str[cmp.len - 1] == '\n') {
+		cmp.len--;
+		if (!cmp.len) {
+			clear_root_wait = true;
+			goto done;
+		}
+	}
 
 	dev = class_find_device(&block_class, NULL, &cmp,
 				&match_dev_by_uuid);
@@ -202,12 +209,13 @@ done:
  *	bangs.
  */
 
-dev_t name_to_dev_t(char *name)
+dev_t name_to_dev_t(const char *name)
 {
 	char s[32];
 	char *p;
 	dev_t res = 0;
 	int part;
+	int n;
 
 #ifdef CONFIG_BLOCK
 	if (strncmp(name, "PARTUUID=", 9) == 0) {
@@ -228,7 +236,7 @@ dev_t name_to_dev_t(char *name)
 				goto fail;
 		} else {
 			res = new_decode_dev(simple_strtoul(name, &p, 16));
-			if (*p)
+			if (*p && *p != '\n')
 				goto fail;
 		}
 		goto done;
@@ -236,15 +244,20 @@ dev_t name_to_dev_t(char *name)
 
 	name += 5;
 	res = Root_NFS;
-	if (strcmp(name, "nfs") == 0)
+	if (strncmp(name, "nfs", 3) == 0)
 		goto done;
 	res = Root_RAM0;
-	if (strcmp(name, "ram") == 0)
+	if (strncmp(name, "ram", 3) == 0)
 		goto done;
 
-	if (strlen(name) > 31)
+	n = strlen(name);
+	if (n != 0 && name[n - 1] == '\n')
+		n--;
+	if (n > 31)
 		goto fail;
-	strcpy(s, name);
+	strncpy(s, name, n);
+	s[n] = '\0';
+
 	for (p = s; *p; p++)
 		if (*p == '/')
 			*p = '!';
-- 
1.7.9.5

[PATCH v3 RFT 2/2] PM / Hibernate: use name_to_dev_t to parse resume

[Sebastian Capella]

Use the name_to_dev_t call to parse the device name echo'd to
to /sys/power/resume.  This imitates the method used in hibernate.c
in software_resume, and allows the resume partition to be specified
using other equivalent device formats as well.  By allowing
/sys/debug/resume to accept the same syntax as the resume=device
parameter, we can parse the resume=device in the init script and
use the resume device directly from the kernel command line.

Signed-off-by: Sebastian Capella <sebastian.capella@linaro.org>
Cc: Len Brown <len.brown@intel.com>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
---
 kernel/power/hibernate.c |   15 ++++-----------
 1 file changed, 4 insertions(+), 11 deletions(-)

diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
index b26f5f1..8b253c2 100644
--- a/kernel/power/hibernate.c
+++ b/kernel/power/hibernate.c
@@ -971,16 +971,11 @@ static ssize_t resume_show(struct kobject *kobj, struct kobj_attribute *attr,
 static ssize_t resume_store(struct kobject *kobj, struct kobj_attribute *attr,
 			    const char *buf, size_t n)
 {
-	unsigned int maj, min;
 	dev_t res;
-	int ret = -EINVAL;
 
-	if (sscanf(buf, "%u:%u", &maj, &min) != 2)
-		goto out;
-
-	res = MKDEV(maj,min);
-	if (maj != MAJOR(res) || min != MINOR(res))
-		goto out;
+	res = name_to_dev_t(buf);
+	if (res == 0)
+		return -EINVAL;
 
 	lock_system_sleep();
 	swsusp_resume_device = res;
@@ -988,9 +983,7 @@ static ssize_t resume_store(struct kobject *kobj, struct kobj_attribute *attr,
 	printk(KERN_INFO "PM: Starting manual resume from disk\n");
 	noresume = 0;
 	software_resume();
-	ret = n;
- out:
-	return ret;
+	return n;
 }
 
 power_attr(resume);
-- 
1.7.9.5

[PATCH v3 RFT 1/2] init/do_mounts.c: ignore final \n in name_to_dev_t

[Pavel Machek]

On Wed 2013-09-18 16:29:01, Sebastian Capella wrote:
> Enhance name_to_dev_t to handle trailing newline characters
> on device paths.  Some inputs to name_to_dev_t may come from
> userspace where oftentimes a '\n' is appended to the path.
> Added const to the name buffer in both the function
> declaration and the prototype to reflect input buffer
> handling.
> 
> By handling trailing newlines in name_to_dev_t, userspace
> buffers may be directly passed to name_to_dev_t without
> modification.
> 
> Signed-off-by: Sebastian Capella <sebastian.capella@linaro.org>
> Cc: Pavel Machek <pavel@ucw.cz>

Reviewed-by: Pavel Machek <pavel@ucw.cz>

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

[PATCH v3 RFT 2/2] PM / Hibernate: use name_to_dev_t to parse resume

[Pavel Machek]

On Wed 2013-09-18 16:29:02, Sebastian Capella wrote:
> Use the name_to_dev_t call to parse the device name echo'd to
> to /sys/power/resume.  This imitates the method used in hibernate.c
> in software_resume, and allows the resume partition to be specified
> using other equivalent device formats as well.  By allowing
> /sys/debug/resume to accept the same syntax as the resume=device
> parameter, we can parse the resume=device in the init script and
> use the resume device directly from the kernel command line.
> 
> Signed-off-by: Sebastian Capella <sebastian.capella@linaro.org>
> Cc: Len Brown <len.brown@intel.com>

Acked-by: Pavel Machek <pavel@ucw.cz>
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html