diff options
| author | Eric Dumazet <edumazet@google.com> | 2024-02-14 08:48:28 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2024-02-17 16:20:41 +0100 |
| commit | 2444a80c1cc2c4240f60f2162abef3797c1803de (patch) | |
| tree | 2a977ffce3acb403fba8704d50edacb7681dcf3e | |
| parent | 5df9197edd731a44682444631d68c2384f381bf1 (diff) | |
kobject: make uevent_seqnum atomic
We will soon no longer acquire uevent_sock_mutex
for most kobject_uevent_net_broadcast() calls,
and also while calling uevent_net_broadcast().
Make uevent_seqnum an atomic64_t to get its own protection.
This fixes a race while reading /sys/kernel/uevent_seqnum.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Christian Brauner <brauner@kernel.org>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Link: https://lore.kernel.org/r/20240214084829.684541-2-edumazet@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | include/linux/kobject.h | 2 | ||||
| -rw-r--r-- | kernel/ksysfs.c | 2 | ||||
| -rw-r--r-- | lib/kobject_uevent.c | 17 |
3 files changed, 11 insertions, 10 deletions
diff --git a/include/linux/kobject.h b/include/linux/kobject.h index c30affcc43b4..c8219505a79f 100644 --- a/include/linux/kobject.h +++ b/include/linux/kobject.h @@ -38,7 +38,7 @@ extern char uevent_helper[]; #endif /* counter to tag the uevent, read only except for the kobject core */ -extern u64 uevent_seqnum; +extern atomic64_t uevent_seqnum; /* * The actions here must match the index to the string array diff --git a/kernel/ksysfs.c b/kernel/ksysfs.c index 1d4bc493b2f4..32ae7fa74a9c 100644 --- a/kernel/ksysfs.c +++ b/kernel/ksysfs.c @@ -39,7 +39,7 @@ static struct kobj_attribute _name##_attr = __ATTR_RW(_name) static ssize_t uevent_seqnum_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf) { - return sysfs_emit(buf, "%llu\n", (unsigned long long)uevent_seqnum); + return sysfs_emit(buf, "%llu\n", (u64)atomic64_read(&uevent_seqnum)); } KERNEL_ATTR_RO(uevent_seqnum); diff --git a/lib/kobject_uevent.c b/lib/kobject_uevent.c index fb9a2f06dd1e..9cb1a7fdaeba 100644 --- a/lib/kobject_uevent.c +++ b/lib/kobject_uevent.c @@ -30,7 +30,7 @@ #include <net/net_namespace.h> -u64 uevent_seqnum; +atomic64_t uevent_seqnum; #ifdef CONFIG_UEVENT_HELPER char uevent_helper[UEVENT_HELPER_PATH_LEN] = CONFIG_UEVENT_HELPER_PATH; #endif @@ -44,7 +44,7 @@ struct uevent_sock { static LIST_HEAD(uevent_sock_list); #endif -/* This lock protects uevent_seqnum and uevent_sock_list */ +/* This lock protects uevent_sock_list */ static DEFINE_MUTEX(uevent_sock_mutex); /* the strings here must match the enum in include/linux/kobject.h */ @@ -583,13 +583,13 @@ int kobject_uevent_env(struct kobject *kobj, enum kobject_action action, break; } - mutex_lock(&uevent_sock_mutex); /* we will send an event, so request a new sequence number */ - retval = add_uevent_var(env, "SEQNUM=%llu", ++uevent_seqnum); - if (retval) { - mutex_unlock(&uevent_sock_mutex); + retval = add_uevent_var(env, "SEQNUM=%llu", + atomic64_inc_return(&uevent_seqnum)); + if (retval) goto exit; - } + + mutex_lock(&uevent_sock_mutex); retval = kobject_uevent_net_broadcast(kobj, env, action_string, devpath); mutex_unlock(&uevent_sock_mutex); @@ -688,7 +688,8 @@ static int uevent_net_broadcast(struct sock *usk, struct sk_buff *skb, int ret; /* bump and prepare sequence number */ - ret = snprintf(buf, sizeof(buf), "SEQNUM=%llu", ++uevent_seqnum); + ret = snprintf(buf, sizeof(buf), "SEQNUM=%llu", + atomic64_inc_return(&uevent_seqnum)); if (ret < 0 || (size_t)ret >= sizeof(buf)) return -ENOMEM; ret++; |