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SUNRPC: Close a race with transport setup and module put

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After we've looked up the transport module, we need to ensure it can't
go away until we've finished running the transport setup code.

Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>
This commit is contained in:
Trond Myklebust 2020-11-10 12:58:22 -05:00
parent d5aa6b22e2
commit 9bccd26461
1 changed files with 33 additions and 11 deletions
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44
net/sunrpc/xprt.c
View file

@ -157,6 +157,32 @@ xprt_class_release(const struct xprt_class *t)
module_put(t->owner);
}
static const struct xprt_class *
xprt_class_find_by_ident_locked(int ident)
{
const struct xprt_class *t;
list_for_each_entry(t, &xprt_list, list) {
if (t->ident != ident)
continue;
if (!try_module_get(t->owner))
continue;
return t;
}
return NULL;
}
static const struct xprt_class *
xprt_class_find_by_ident(int ident)
{
const struct xprt_class *t;
spin_lock(&xprt_list_lock);
t = xprt_class_find_by_ident_locked(ident);
spin_unlock(&xprt_list_lock);
return t;
}
static const struct xprt_class *
xprt_class_find_by_netid_locked(const char *netid)
{
@ -1929,21 +1955,17 @@ static void xprt_init(struct rpc_xprt *xprt, struct net *net)
struct rpc_xprt *xprt_create_transport(struct xprt_create *args)
{
struct rpc_xprt *xprt;
struct xprt_class *t;
const struct xprt_class *t;
spin_lock(&xprt_list_lock);
list_for_each_entry(t, &xprt_list, list) {
if (t->ident == args->ident) {
spin_unlock(&xprt_list_lock);
goto found;
}
t = xprt_class_find_by_ident(args->ident);
if (!t) {
dprintk("RPC: transport (%d) not supported\n", args->ident);
return ERR_PTR(-EIO);
}
spin_unlock(&xprt_list_lock);
dprintk("RPC: transport (%d) not supported\n", args->ident);
return ERR_PTR(-EIO);
found:
xprt = t->setup(args);
xprt_class_release(t);
if (IS_ERR(xprt))
goto out;
if (args->flags & XPRT_CREATE_NO_IDLE_TIMEOUT)