Re: [PATCH] nbd: reclassify u->iolock of AF_UNIX sockets

[Christian Borntraeger]

Am 14.07.26 um 18:19 schrieb Christian Borntraeger:
> Am 13.07.26 um 20:14 schrieb Christian Borntraeger:
>
> I just realized I had my kernel.org address in from.
> question is, is this the right fix and shall I do a proper patch wit correct from and signoff.
>
> [..]
>
> > diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
> > index 8f10762e90ef..a811e431b47a 100644
> > --- a/drivers/block/nbd.c
> > +++ b/drivers/block/nbd.c
> > @@ -32,6 +32,7 @@
> >   #include <linux/err.h>
> >   #include <linux/kernel.h>
> >   #include <linux/slab.h>
> > +#include <net/af_unix.h>
> >   #include <net/sock.h>
> >   #include <linux/net.h>
> >   #include <linux/kthread.h>
> > @@ -1241,6 +1242,7 @@ static struct socket *nbd_get_socket(struct nbd_device *nbd, unsigned long fd,
> >   #ifdef CONFIG_DEBUG_LOCK_ALLOC
> >   static struct lock_class_key nbd_key[3];
> >   static struct lock_class_key nbd_slock_key[3];
> > +static struct lock_class_key nbd_unix_iolock_key;
> >   static void nbd_reclassify_socket(struct socket *sock)
> >   {
> > @@ -1267,6 +1269,17 @@ static void nbd_reclassify_socket(struct socket *sock)
> >                             &nbd_slock_key[2],
> >                             "sk_lock-AF_UNIX-NBD",
> >                             &nbd_key[2]);
> > +        /*
> > +         * The AF_UNIX stream recvmsg/sendmsg paths serialize on
> > +         * u->iolock, not sk_lock, so it must be reclassified as
> > +         * well.  A held mutex cannot be reclassified; skip it in
> > +         * that case, as sock_allow_reclassification() does for
> > +         * sk_lock.
> > +         */
> > +        if (!mutex_is_locked(&unix_sk(sk)->iolock))
> > +            lockdep_set_class_and_name(&unix_sk(sk)->iolock,
> > +                           &nbd_unix_iolock_key,
> > +                           "&u->iolock-NBD");
> >           break;
> >       }
> >   }


And when you are at it, maybe also do the reclassification for NBD_CMD_RECONFIGURE

@@ -1371,6 +1371,7 @@ static int nbd_reconnect_socket(struct nbd_device *nbd, unsigned long arg)
        sock = nbd_get_socket(nbd, arg, &err);
        if (!sock)
                return err;
+       nbd_reclassify_socket(sock);
 
        args = kzalloc_obj(*args);
        if (!args) {