[PATCH v6 0/2] hibernation related patches

[PATCH v6 0/2] hibernation related patches

[Sebastian Capella]

Patchset related to hibernation resume:
  - enhancement to make the use of an existing resume file more general
  - add kstrimdup function which trims and duplicates a string

  Both patches are based on the 3.13 tag.  This was tested on a
  Beaglebone black with partial hibernation support, and compiled for
  x86_64.

[PATCH v6 1/2] mm: add kstrimdup function
  include/linux/string.h |    1 +
  mm/util.c              |   30 ++++++++++++++++++++++++++++++
  2 files changed, 31 insertions(+)

  Adds the kstrimdup function to duplicate and trim whitespace
  from a string.  This is useful for working with user input to
  sysfs.

[PATCH v6 2/2] PM / Hibernate: use name_to_dev_t to parse resume
  kernel/power/hibernate.c |   33 +++++++++++++++++----------------
  1 file changed, 17 insertions(+), 16 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 v6:
--------------
* Revert tricky / confusing while loop indexing

Changes in v5:
--------------
* Change kstrimdup to minimize allocated memory.  Now allocates only
  the memory needed for the string instead of using strim.

Changes in v4:
--------------
* Dropped name_to_dev_t rework in favor of adding kstrimdup
* adjusted resume_store

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 v6 1/2] mm: add kstrimdup function

[Sebastian Capella]

kstrimdup creates a whitespace-trimmed duplicate of the passed
in null-terminated string.  This is useful for strings coming
from sysfs that often include trailing whitespace due to user
input.

Thanks to Joe Perches for this implementation.

Signed-off-by: Sebastian Capella <sebastian.capella@linaro.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Joe Perches <joe@perches.com>
Cc: Mikulas Patocka <mpatocka@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Rik van Riel <riel@redhat.com> (commit_signer:5/10=50%)
Cc: Michel Lespinasse <walken@google.com>
Cc: Shaohua Li <shli@kernel.org>
Cc: Jerome Marchand <jmarchan@redhat.com>
Cc: Mikulas Patocka <mpatocka@redhat.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
---
 include/linux/string.h |    1 +
 mm/util.c              |   30 ++++++++++++++++++++++++++++++
 2 files changed, 31 insertions(+)

diff --git a/include/linux/string.h b/include/linux/string.h
index ac889c5..f29f9a0 100644
--- a/include/linux/string.h
+++ b/include/linux/string.h
@@ -114,6 +114,7 @@ void *memchr_inv(const void *s, int c, size_t n);
 
 extern char *kstrdup(const char *s, gfp_t gfp);
 extern char *kstrndup(const char *s, size_t len, gfp_t gfp);
+extern char *kstrimdup(const char *s, gfp_t gfp);
 extern void *kmemdup(const void *src, size_t len, gfp_t gfp);
 
 extern char **argv_split(gfp_t gfp, const char *str, int *argcp);
diff --git a/mm/util.c b/mm/util.c
index 808f375..a8b731c 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -1,6 +1,7 @@
 #include <linux/mm.h>
 #include <linux/slab.h>
 #include <linux/string.h>
+#include <linux/ctype.h>
 #include <linux/export.h>
 #include <linux/err.h>
 #include <linux/sched.h>
@@ -63,6 +64,35 @@ char *kstrndup(const char *s, size_t max, gfp_t gfp)
 EXPORT_SYMBOL(kstrndup);
 
 /**
+ * kstrimdup - Trim and copy a %NUL terminated string.
+ * @s: the string to trim and duplicate
+ * @gfp: the GFP mask used in the kmalloc() call when allocating memory
+ *
+ * Returns an address, which the caller must kfree, containing
+ * a duplicate of the passed string with leading and/or trailing
+ * whitespace (as defined by isspace) removed.
+ */
+char *kstrimdup(const char *s, gfp_t gfp)
+{
+	char *buf;
+	char *begin = skip_spaces(s);
+	size_t len = strlen(begin);
+
+	while (len && isspace(begin[len - 1]))
+		len--;
+
+	buf = kmalloc_track_caller(len + 1, gfp);
+	if (!buf)
+		return NULL;
+
+	memcpy(buf, begin, len);
+	buf[len] = '\0';
+
+	return buf;
+}
+EXPORT_SYMBOL(kstrimdup);
+
+/**
  * kmemdup - duplicate region of memory
  *
  * @src: memory region to duplicate
-- 
1.7.9.5

[PATCH v6 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>
Acked-by: Pavel Machek <pavel@ucw.cz>
Cc: Len Brown <len.brown@intel.com>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
---
 kernel/power/hibernate.c |   33 +++++++++++++++++----------------
 1 file changed, 17 insertions(+), 16 deletions(-)

diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
index 0121dab..49d7a37 100644
--- a/kernel/power/hibernate.c
+++ b/kernel/power/hibernate.c
@@ -972,26 +972,27 @@ 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;
+	char *name = kstrimdup(buf, GFP_KERNEL);
 
-	if (sscanf(buf, "%u:%u", &maj, &min) != 2)
-		goto out;
+	if (name == NULL)
+		return -ENOMEM;
 
-	res = MKDEV(maj,min);
-	if (maj != MAJOR(res) || min != MINOR(res))
-		goto out;
+	res = name_to_dev_t(name);
 
-	lock_system_sleep();
-	swsusp_resume_device = res;
-	unlock_system_sleep();
-	printk(KERN_INFO "PM: Starting manual resume from disk\n");
-	noresume = 0;
-	software_resume();
-	ret = n;
- out:
-	return ret;
+	if (res != 0) {
+		lock_system_sleep();
+		swsusp_resume_device = res;
+		unlock_system_sleep();
+		printk(KERN_INFO "PM: Starting manual resume from disk\n");
+		noresume = 0;
+		software_resume();
+	} else {
+		n = -EINVAL;
+	}
+
+	kfree(name);
+	return n;
 }
 
 power_attr(resume);
-- 
1.7.9.5

Re: [PATCH v6 1/2] mm: add kstrimdup function

[David Rientjes]

On Thu, 30 Jan 2014, Sebastian Capella wrote:

> kstrimdup creates a whitespace-trimmed duplicate of the passed
> in null-terminated string.  This is useful for strings coming
> from sysfs that often include trailing whitespace due to user
> input.
> 
> Thanks to Joe Perches for this implementation.
> 
> Signed-off-by: Sebastian Capella <sebastian.capella@linaro.org>

Acked-by: David Rientjes <rientjes@google.com>

> ---
>  include/linux/string.h |    1 +
>  mm/util.c              |   30 ++++++++++++++++++++++++++++++
>  2 files changed, 31 insertions(+)
> 
> diff --git a/include/linux/string.h b/include/linux/string.h
> index ac889c5..f29f9a0 100644
> --- a/include/linux/string.h
> +++ b/include/linux/string.h
> @@ -114,6 +114,7 @@ void *memchr_inv(const void *s, int c, size_t n);
>  
>  extern char *kstrdup(const char *s, gfp_t gfp);
>  extern char *kstrndup(const char *s, size_t len, gfp_t gfp);
> +extern char *kstrimdup(const char *s, gfp_t gfp);
>  extern void *kmemdup(const void *src, size_t len, gfp_t gfp);
>  
>  extern char **argv_split(gfp_t gfp, const char *str, int *argcp);
> diff --git a/mm/util.c b/mm/util.c
> index 808f375..a8b731c 100644
> --- a/mm/util.c
> +++ b/mm/util.c
> @@ -1,6 +1,7 @@
>  #include <linux/mm.h>
>  #include <linux/slab.h>
>  #include <linux/string.h>
> +#include <linux/ctype.h>
>  #include <linux/export.h>
>  #include <linux/err.h>
>  #include <linux/sched.h>
> @@ -63,6 +64,35 @@ char *kstrndup(const char *s, size_t max, gfp_t gfp)
>  EXPORT_SYMBOL(kstrndup);
>  
>  /**
> + * kstrimdup - Trim and copy a %NUL terminated string.
> + * @s: the string to trim and duplicate
> + * @gfp: the GFP mask used in the kmalloc() call when allocating memory
> + *
> + * Returns an address, which the caller must kfree, containing
> + * a duplicate of the passed string with leading and/or trailing
> + * whitespace (as defined by isspace) removed.
> + */
> +char *kstrimdup(const char *s, gfp_t gfp)
> +{
> +	char *buf;
> +	char *begin = skip_spaces(s);

This could be const.

> +	size_t len = strlen(begin);
> +
> +	while (len && isspace(begin[len - 1]))
> +		len--;
> +
> +	buf = kmalloc_track_caller(len + 1, gfp);
> +	if (!buf)
> +		return NULL;
> +
> +	memcpy(buf, begin, len);
> +	buf[len] = '\0';
> +
> +	return buf;
> +}
> +EXPORT_SYMBOL(kstrimdup);
> +
> +/**
>   * kmemdup - duplicate region of memory
>   *
>   * @src: memory region to duplicate