Commit 094eca37 authored by Trond Myklebust's avatar Trond Myklebust Committed by Anna Schumaker
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NFSv4: Fix up RCU annotations for struct nfs_netns_client 



The identifier is read as an RCU protected string. Its value may
be changed during the lifetime of the network namespace by writing
a new string into the sysfs pseudofile (at which point, we free the
old string only after a call to synchronize_rcu()).

Signed-off-by: default avatarTrond Myklebust <trond.myklebust@hammerspace.com>
Signed-off-by: default avatarAnna Schumaker <Anna.Schumaker@Netapp.com>
parent 61ca2c4a

fs/nfs/sysfs.c

+8 −3
Original line number Diff line number Diff line
@@ -79,7 +79,12 @@ static ssize_t nfs_netns_identifier_show(struct kobject *kobj, 
	struct nfs_netns_client *c = container_of(kobj,

			struct nfs_netns_client,

			kobject);

	return scnprintf(buf, PAGE_SIZE, "%s\n", c->identifier);

	ssize_t ret;



	rcu_read_lock();

	ret = scnprintf(buf, PAGE_SIZE, "%s\n", rcu_dereference(c->identifier));

	rcu_read_unlock();

	return ret;

}



/* Strip trailing '\n' */
@@ -107,7 +112,7 @@ static ssize_t nfs_netns_identifier_store(struct kobject *kobj, 
	p = kmemdup_nul(buf, len, GFP_KERNEL);

	if (!p)

		return -ENOMEM;

	old = xchg(&c->identifier, p);

	old = rcu_dereference_protected(xchg(&c->identifier, (char __rcu *)p), 1);

	if (old) {

		synchronize_rcu();

		kfree(old);
@@ -121,7 +126,7 @@ static void nfs_netns_client_release(struct kobject *kobj) 
			struct nfs_netns_client,

			kobject);



	kfree(c->identifier);

	kfree(rcu_dereference_raw(c->identifier));

	kfree(c);

}

fs/nfs/sysfs.h

+1 −1
Original line number Diff line number Diff line
@@ -11,7 +11,7 @@ 
struct nfs_netns_client {

	struct kobject kobject;

	struct net *net;

	const char *identifier;

	const char __rcu *identifier;

};



extern struct kobject *nfs_client_kobj;