linux-kernel - Re: [PATCH] PROC_FS: get and set the smp affinity of tasks by read-write /proc/<pid>/smp

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <91b13c310801040738h75465241wa1179d0e06131354@mail.gmail.com>
Date:	Fri, 4 Jan 2008 23:38:52 +0800
From:	"rae l" <crquan@...il.com>
To:	"Paul Jackson" <pj@....com>
Cc:	akpm@...ux-foundation.org, viro@...iv.linux.org.uk,
	torvalds@...ux-foundation.org, linux-kernel@...r.kernel.org,
	emdow@...ibm.com
Subject: Re: [PATCH] PROC_FS: get and set the smp affinity of tasks by read-write /proc/<pid>/smp_affinity

>From d2be88406fdc1d28a7cf0b1a13ca761d625820a5 Mon Sep 17 00:00:00 2001
From: Denis Cheng <crquan@...il.com>
Date: Fri, 4 Jan 2008 14:50:54 +0800
Subject: [PATCH] PROC_FS: get and set the smp affinity of tasks by
read-write /proc/<pid>/smp_affinity

this adds a read-write /proc/<pid>/smp_affinity entry,
just like what /proc/irq/<irq>/smp_affinity does,
so now we can get and set the affinity of tasks by procfs,
this is especially useful used in shell scripts.

this also adds a read-write /proc/<pid>/tasks/<tid>/smp_affinity
for the same purpose.

Cc: Eli M Dow <emdow@...ibm.com>
Signed-off-by: Denis Cheng <crquan@...il.com>
---
length check copied from kernel/irq/proc.c, now 'page' buffer couldn't
be overrun,

Another way, although Documentation/filesystems/proc.txt is heavily outdated,
I'll add introduction of smp_affinity.

 fs/proc/base.c |   65 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 files changed, 65 insertions(+), 0 deletions(-)

diff --git a/fs/proc/base.c b/fs/proc/base.c
index 7411bfb..d768d66 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -1083,6 +1083,65 @@ static const struct file_operations
proc_pid_sched_operations = {

 #endif

+#ifdef CONFIG_SMP
+static ssize_t smp_affinity_read(struct file *file,
+		char __user *buf, size_t count, loff_t *ppos)
+{
+	cpumask_t mask;
+	char *page;
+	ssize_t length;
+	pid_t pid = pid_nr(proc_pid(file->f_dentry->d_inode));
+
+	length = sched_getaffinity(pid, &mask);
+	if (length < 0)
+		return length;
+
+	if (count > PROC_BLOCK_SIZE)
+		count = PROC_BLOCK_SIZE;
+
+	page = (char *)__get_free_page(GFP_TEMPORARY);
+	if (!page) {
+		length = -ENOMEM;
+		goto out;
+	}
+
+	length = cpumask_scnprintf(page, count, mask);
+	if (count - length < 2) {
+		length = -EINVAL;
+		goto out_free_page;
+	}
+	length += sprintf(page + length, "\n");
+	length = simple_read_from_buffer(buf, count, ppos, page, length);
+
+out_free_page:
+	free_page((unsigned long)page);
+out:
+	return length;
+}
+
+static ssize_t smp_affinity_write(struct file *file,
+		const char __user *buf, size_t count, loff_t *ppos)
+{
+	cpumask_t mask;
+	int ret;
+	pid_t pid = pid_nr(proc_pid(file->f_dentry->d_inode));
+
+	ret = cpumask_parse_user(buf, count, mask);
+	if (ret < 0)
+		return ret;
+	ret = sched_setaffinity(pid, mask);
+	if (ret < 0)
+		return ret;
+
+	return count;
+}
+
+static const struct file_operations proc_smp_affinity_operations = {
+	.read  = smp_affinity_read,
+	.write = smp_affinity_write,
+};
+#endif
+
 static void *proc_pid_follow_link(struct dentry *dentry, struct nameidata *nd)
 {
 	struct inode *inode = dentry->d_inode;
@@ -2230,6 +2289,9 @@ static const struct pid_entry tgid_base_stuff[] = {
 #ifdef CONFIG_SCHEDSTATS
 	INF("schedstat",  S_IRUGO, pid_schedstat),
 #endif
+#ifdef CONFIG_SMP
+	REG("smp_affinity", S_IRUGO|S_IWUSR, smp_affinity),
+#endif
 #ifdef CONFIG_PROC_PID_CPUSET
 	REG("cpuset",     S_IRUGO, cpuset),
 #endif
@@ -2555,6 +2617,9 @@ static const struct pid_entry tid_base_stuff[] = {
 #ifdef CONFIG_SCHEDSTATS
 	INF("schedstat", S_IRUGO, pid_schedstat),
 #endif
+#ifdef CONFIG_SMP
+	REG("smp_affinity", S_IRUGO|S_IWUSR, smp_affinity),
+#endif
 #ifdef CONFIG_PROC_PID_CPUSET
 	REG("cpuset",    S_IRUGO, cpuset),
 #endif
-- 
1.5.3.5
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/