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Commit e73d2c61 authored by Paul Menage's avatar Paul Menage Committed by Linus Torvalds
Browse files

CGroups _s64 files: add cgroups read_s64/write_s64 file methods 



These patches add cgroups read_s64 and write_s64 control file methods (the
signed equivalent of read_u64/write_u64) and use them to implement the
cpu.rt_runtime_us control file in the CFS cgroup subsystem.

This patch:

These are the signed equivalents of the read_u64/write_u64 methods

Signed-off-by: default avatarPaul Menage <menage@google.com>
Acked-by: default avatarPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 418d7d87

include/linux/cgroup.h

+8 −0
Original line number Diff line number Diff line
@@ -215,6 +215,10 @@ struct cftype { 
	 * single integer. Use it in place of read()

	 */

	u64 (*read_u64) (struct cgroup *cgrp, struct cftype *cft);

	/*

	 * read_s64() is a signed version of read_u64()

	 */

	s64 (*read_s64) (struct cgroup *cgrp, struct cftype *cft);

	/*

	 * read_map() is used for defining a map of key/value

	 * pairs. It should call cb->fill(cb, key, value) for each
@@ -234,6 +238,10 @@ struct cftype { 
	 * userspace. Use in place of write(); return 0 or error.

	 */

	int (*write_u64) (struct cgroup *cgrp, struct cftype *cft, u64 val);

	/*

	 * write_s64() is a signed version of write_u64()

	 */

	int (*write_s64) (struct cgroup *cgrp, struct cftype *cft, s64 val);



	int (*release) (struct inode *inode, struct file *file);

};

kernel/cgroup.c

+28 −10
Original line number Diff line number Diff line
@@ -1299,14 +1299,13 @@ enum cgroup_filetype { 
	FILE_RELEASE_AGENT,

};



static ssize_t cgroup_write_u64(struct cgroup *cgrp, struct cftype *cft,

static ssize_t cgroup_write_X64(struct cgroup *cgrp, struct cftype *cft,

				struct file *file,

				const char __user *userbuf,

				size_t nbytes, loff_t *unused_ppos)

{

	char buffer[64];

	int retval = 0;

	u64 val;

	char *end;



	if (!nbytes)
@@ -1318,12 +1317,17 @@ static ssize_t cgroup_write_u64(struct cgroup *cgrp, struct cftype *cft, 


	buffer[nbytes] = 0;     /* nul-terminate */

	strstrip(buffer);

	val = simple_strtoull(buffer, &end, 0);

	if (cft->write_u64) {

		u64 val = simple_strtoull(buffer, &end, 0);

		if (*end)

			return -EINVAL;



	/* Pass to subsystem */

		retval = cft->write_u64(cgrp, cft, val);

	} else {

		s64 val = simple_strtoll(buffer, &end, 0);

		if (*end)

			return -EINVAL;

		retval = cft->write_s64(cgrp, cft, val);

	}

	if (!retval)

		retval = nbytes;

	return retval;
@@ -1404,8 +1408,8 @@ static ssize_t cgroup_file_write(struct file *file, const char __user *buf, 
		return -ENODEV;

	if (cft->write)

		return cft->write(cgrp, cft, file, buf, nbytes, ppos);

	if (cft->write_u64)

		return cgroup_write_u64(cgrp, cft, file, buf, nbytes, ppos);

	if (cft->write_u64 || cft->write_s64)

		return cgroup_write_X64(cgrp, cft, file, buf, nbytes, ppos);

	return -EINVAL;

}
@@ -1421,6 +1425,18 @@ static ssize_t cgroup_read_u64(struct cgroup *cgrp, struct cftype *cft, 
	return simple_read_from_buffer(buf, nbytes, ppos, tmp, len);

}



static ssize_t cgroup_read_s64(struct cgroup *cgrp, struct cftype *cft,

			       struct file *file,

			       char __user *buf, size_t nbytes,

			       loff_t *ppos)

{

	char tmp[64];

	s64 val = cft->read_s64(cgrp, cft);

	int len = sprintf(tmp, "%lld\n", (long long) val);



	return simple_read_from_buffer(buf, nbytes, ppos, tmp, len);

}



static ssize_t cgroup_common_file_read(struct cgroup *cgrp,

					  struct cftype *cft,

					  struct file *file,
@@ -1477,6 +1493,8 @@ static ssize_t cgroup_file_read(struct file *file, char __user *buf, 
		return cft->read(cgrp, cft, file, buf, nbytes, ppos);

	if (cft->read_u64)

		return cgroup_read_u64(cgrp, cft, file, buf, nbytes, ppos);

	if (cft->read_s64)

		return cgroup_read_s64(cgrp, cft, file, buf, nbytes, ppos);

	return -EINVAL;

}