The patch titled
sysctl: convert hotplug helper string to proc_rcu_string()
has been removed from the -mm tree. Its filename was
sysctl-convert-hotplug-helper-string-to-proc_rcu_string.patch
This patch was dropped because an updated version will be merged
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: sysctl: convert hotplug helper string to proc_rcu_string()
From: Andi Kleen <andi@xxxxxxxxxxxxxx>
This avoids races with lockless sysctl.
Also saves ~220 bytes in the data segment for default kernels.
I also moved the code into a separate function because the original
was very long.
Signed-off-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Cc: "Paul E. McKenney" <paulmck@xxxxxxxxxx>
Cc: Russell King <rmk+lkml@xxxxxxxxxxxxxxxx>
Cc: Sam Ravnborg <sam@xxxxxxxxxxxx>
Cc: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
Acked-by: Greg Kroah-Hartman <gregkh@xxxxxxx>
Cc: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/kobject.h | 2 -
kernel/sysctl.c | 2 -
lib/kobject_uevent.c | 50 ++++++++++++++++++++++++--------------
3 files changed, 34 insertions(+), 20 deletions(-)
diff -puN include/linux/kobject.h~sysctl-convert-hotplug-helper-string-to-proc_rcu_string include/linux/kobject.h
--- a/include/linux/kobject.h~sysctl-convert-hotplug-helper-string-to-proc_rcu_string
+++ a/include/linux/kobject.h
@@ -31,7 +31,7 @@
#define UEVENT_BUFFER_SIZE 2048 /* buffer for the variables */
/* path to the userspace helper executed on an event */
-extern char uevent_helper[];
+extern char *uevent_helper;
/* counter to tag the uevent, read only except for the kobject core */
extern u64 uevent_seqnum;
diff -puN kernel/sysctl.c~sysctl-convert-hotplug-helper-string-to-proc_rcu_string kernel/sysctl.c
--- a/kernel/sysctl.c~sysctl-convert-hotplug-helper-string-to-proc_rcu_string
+++ a/kernel/sysctl.c
@@ -557,7 +557,7 @@ static struct ctl_table kern_table[] = {
.data = &uevent_helper,
.maxlen = UEVENT_HELPER_PATH_LEN,
.mode = 0644,
- .proc_handler = proc_dostring,
+ .proc_handler = proc_rcu_string,
},
#endif
#ifdef CONFIG_CHR_DEV_SG
diff -puN lib/kobject_uevent.c~sysctl-convert-hotplug-helper-string-to-proc_rcu_string lib/kobject_uevent.c
--- a/lib/kobject_uevent.c~sysctl-convert-hotplug-helper-string-to-proc_rcu_string
+++ a/lib/kobject_uevent.c
@@ -22,11 +22,12 @@
#include <linux/socket.h>
#include <linux/skbuff.h>
#include <linux/netlink.h>
+#include <linux/rcustring.h>
#include <net/sock.h>
u64 uevent_seqnum;
-char uevent_helper[UEVENT_HELPER_PATH_LEN] = CONFIG_UEVENT_HELPER_PATH;
+char *uevent_helper = CONFIG_UEVENT_HELPER_PATH;
static DEFINE_SPINLOCK(sequence_lock);
#if defined(CONFIG_NET)
static struct sock *uevent_sock;
@@ -76,6 +77,34 @@ out:
return ret;
}
+/* Call an external helper executable. */
+static int uevent_call_helper(const char *subsystem, struct kobj_uevent_env *env)
+{
+ char *argv[3];
+ char *helper;
+ int retval;
+
+ helper = access_rcu_string(&uevent_helper, UEVENT_HELPER_PATH_LEN, GFP_KERNEL);
+ if (!helper)
+ return -ENOMEM;
+
+ retval = -E2BIG;
+ argv[0] = helper;
+ argv[1] = (char *)subsystem;
+ argv[2] = NULL;
+ retval = add_uevent_var(env, "HOME=/");
+ if (retval)
+ goto error;
+ retval = add_uevent_var(env, "PATH=/sbin:/bin:/usr/sbin:/usr/bin");
+ if (retval)
+ goto error;
+
+ retval = call_usermodehelper(argv[0], argv, env->envp, UMH_WAIT_EXEC);
+error:
+ kfree(helper);
+ return retval;
+}
+
/**
* kobject_uevent_env - send an uevent with environmental data
*
@@ -243,23 +272,8 @@ int kobject_uevent_env(struct kobject *k
#endif
/* call uevent_helper, usually only enabled during early boot */
- if (uevent_helper[0]) {
- char *argv [3];
-
- argv [0] = uevent_helper;
- argv [1] = (char *)subsystem;
- argv [2] = NULL;
- retval = add_uevent_var(env, "HOME=/");
- if (retval)
- goto exit;
- retval = add_uevent_var(env,
- "PATH=/sbin:/bin:/usr/sbin:/usr/bin");
- if (retval)
- goto exit;
-
- retval = call_usermodehelper(argv[0], argv,
- env->envp, UMH_WAIT_EXEC);
- }
+ if (uevent_helper[0])
+ retval = uevent_call_helper(subsystem, env);
exit:
kfree(devpath);
_
Patches currently in -mm which might be from andi@xxxxxxxxxxxxxx are
mm-introduce-dump_page-and-print-symbolic-flag-names.patch
linux-next.patch
hardware-latency-detector-remove-default-m.patch
modpost-support-objects-with-more-than-64k-sections.patch
tracehooks-kill-some-pt_ptraced-checks.patch
tracehooks-check-pt_ptraced-before-reporting-the-single-step.patch
ptrace_signal-check-pt_ptraced-before-reporting-a-signal.patch
export-__ptrace_detach-and-do_notify_parent_cldstop.patch
reorder-the-code-in-kernel-ptracec.patch
implement-utrace-ptrace.patch
utrace-core.patch
sysctl-convert-hotplug-helper-string-to-proc_rcu_string.patch
sysctl-use-rcu-protected-sysctl-for-ocfs-group-add-helper.patch
sysctl-fix-up-remaining-references-to-uevent_helper.patch
sysctl-fix-up-remaining-references-to-uevent_helper-fix.patch
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