From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bart Van Assche Date: Thu, 08 Oct 2020 02:15:49 +0000 Subject: Re: [PATCH 1/2] target: iscsi: prevent a race condition in iscsit_unmap_cmd() Message-Id: <1bff131d-d451-2597-7751-fac0269a6e37@acm.org> List-Id: References: <20201007145326.56850-1-mlombard@redhat.com> <20201007145326.56850-2-mlombard@redhat.com> In-Reply-To: <20201007145326.56850-2-mlombard@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Maurizio Lombardi , martin.petersen@oracle.com Cc: linux-scsi@vger.kernel.org, target-devel@vger.kernel.org, michael.christie@oracle.com Archived-At: List-Archive: List-Post: On 2020-10-07 07:53, Maurizio Lombardi wrote: > A potential race condition may occur in iscsit_unmap_cmd() if the > __iscsit_free_cmd() function is called by two different threads. > > This patch adds a spinlock to serialize the calls to > iscsit_unmap_cmd() > > Signed-off-by: Maurizio Lombardi > --- > drivers/target/iscsi/iscsi_target_login.c | 1 + > drivers/target/iscsi/iscsi_target_util.c | 5 ++++- > include/target/iscsi/iscsi_target_core.h | 1 + > 3 files changed, 6 insertions(+), 1 deletion(-) > > diff --git a/drivers/target/iscsi/iscsi_target_login.c b/drivers/target/iscsi/iscsi_target_login.c > index 893d1b406c29..e16ceee87bba 100644 > --- a/drivers/target/iscsi/iscsi_target_login.c > +++ b/drivers/target/iscsi/iscsi_target_login.c > @@ -1110,6 +1110,7 @@ static struct iscsi_conn *iscsit_alloc_conn(struct iscsi_np *np) > spin_lock_init(&conn->nopin_timer_lock); > spin_lock_init(&conn->response_queue_lock); > spin_lock_init(&conn->state_lock); > + spin_lock_init(&conn->unmap_cmd_lock); > > timer_setup(&conn->nopin_response_timer, > iscsit_handle_nopin_response_timeout, 0); > diff --git a/drivers/target/iscsi/iscsi_target_util.c b/drivers/target/iscsi/iscsi_target_util.c > index 45ba07c6ec27..3082f5bde9fa 100644 > --- a/drivers/target/iscsi/iscsi_target_util.c > +++ b/drivers/target/iscsi/iscsi_target_util.c > @@ -755,8 +755,11 @@ void __iscsit_free_cmd(struct iscsi_cmd *cmd, bool check_queues) > iscsit_remove_cmd_from_response_queue(cmd, conn); > } > > - if (conn && conn->conn_transport->iscsit_unmap_cmd) > + if (conn && conn->conn_transport->iscsit_unmap_cmd) { > + spin_lock(&conn->unmap_cmd_lock); > conn->conn_transport->iscsit_unmap_cmd(conn, cmd); > + spin_unlock(&conn->unmap_cmd_lock); > + } > } This looks weird to me. Shouldn't the iSCSI target code make sure that __iscsit_free_cmd() is called once per command instead of allowing concurrent calls of that function and serializing iscsit_unmap_cmd() calls? Thanks, Bart.