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

[Christian Borntraeger <borntraeger@linux.ibm.com>]

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;
>   	}
>   }