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SubjectRe: [PATCH] block: drbd: remove a stay unlock in __drbd_send_protocol()
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Hi Dan,

yes, your patch it obviously correct. The comment you are
referring to is badly worded. We will remove it.

Jens,

are you taking this patch as it is?

best regards,
Phil

Am Donnerstag, 7. November 2019, 08:48:47 CET schrieb Dan Carpenter:
> There are two callers of this function and they both unlock the mutex so
> this ends up being a double unlock.
>
> Fixes: 44ed167da748 ("drbd: rcu_read_lock() and rcu_dereference() for
> tconn->net_conf") Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> ---
> Static analisys. Not tested. There is a comment about the lock next to
> the caller in drbd_nl.c that I didn't understand:
>
> drivers/block/drbd/drbd_nl.c
> 2509 crypto_free_shash(connection->integrity_tfm);
> 2510 connection->integrity_tfm = crypto.integrity_tfm;
> 2511 if (connection->cstate >= C_WF_REPORT_PARAMS &&
> connection->agreed_pro_version >= 100) 2512 /* Do this
> without trying to take connection->data.mutex again. */
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ What does this
> mean? We're already holding that lock. We took it near the start of the
> function.
>
> 2513 __drbd_send_protocol(connection, P_PROTOCOL_UPDATE);
> 2514
> 2515 crypto_free_shash(connection->cram_hmac_tfm);
> 2516 connection->cram_hmac_tfm = crypto.cram_hmac_tfm;
> 2517
> 2518 mutex_unlock(&connection->resource->conf_update);
> 2519 mutex_unlock(&connection->data.mutex);
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> Unlocked here.
>
> drivers/block/drbd/drbd_main.c | 1 -
> 1 file changed, 1 deletion(-)
>
> diff --git a/drivers/block/drbd/drbd_main.c b/drivers/block/drbd/drbd_main.c
> index 5b248763a672..a18155cdce41 100644
> --- a/drivers/block/drbd/drbd_main.c
> +++ b/drivers/block/drbd/drbd_main.c
> @@ -786,7 +786,6 @@ int __drbd_send_protocol(struct drbd_connection
> *connection, enum drbd_packet cm
>
> if (nc->tentative && connection->agreed_pro_version < 92) {
> rcu_read_unlock();
> - mutex_unlock(&sock->mutex);
> drbd_err(connection, "--dry-run is not supported by peer");
> return -EOPNOTSUPP;
> }


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