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 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. 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[73.241.217.19]) by smtp.gmail.com with ESMTPSA id o6sm4018613pjp.33.2020.10.07.19.15.50 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 07 Oct 2020 19:15:51 -0700 (PDT) Subject: Re: [PATCH 1/2] target: iscsi: prevent a race condition in iscsit_unmap_cmd() To: Maurizio Lombardi , martin.petersen@oracle.com Cc: linux-scsi@vger.kernel.org, target-devel@vger.kernel.org, michael.christie@oracle.com References: <20201007145326.56850-1-mlombard@redhat.com> <20201007145326.56850-2-mlombard@redhat.com> From: Bart Van Assche Autocrypt: addr=bvanassche@acm.org; prefer-encrypt=mutual; keydata= mQENBFSOu4oBCADcRWxVUvkkvRmmwTwIjIJvZOu6wNm+dz5AF4z0FHW2KNZL3oheO3P8UZWr LQOrCfRcK8e/sIs2Y2D3Lg/SL7qqbMehGEYcJptu6mKkywBfoYbtBkVoJ/jQsi2H0vBiiCOy fmxMHIPcYxaJdXxrOG2UO4B60Y/BzE6OrPDT44w4cZA9DH5xialliWU447Bts8TJNa3lZKS1 AvW1ZklbvJfAJJAwzDih35LxU2fcWbmhPa7EO2DCv/LM1B10GBB/oQB5kvlq4aA2PSIWkqz4 3SI5kCPSsygD6wKnbRsvNn2mIACva6VHdm62A7xel5dJRfpQjXj2snd1F/YNoNc66UUTABEB AAG0JEJhcnQgVmFuIEFzc2NoZSA8YnZhbmFzc2NoZUBhY20ub3JnPokBOQQTAQIAIwUCVI67 igIbAwcLCQgHAwIBBhUIAgkKCwQWAgMBAh4BAheAAAoJEHFcPTXFzhAJ8QkH/1AdXblKL65M Y1Zk1bYKnkAb4a98LxCPm/pJBilvci6boefwlBDZ2NZuuYWYgyrehMB5H+q+Kq4P0IBbTqTa jTPAANn62A6jwJ0FnCn6YaM9TZQjM1F7LoDX3v+oAkaoXuq0dQ4hnxQNu792bi6QyVdZUvKc macVFVgfK9n04mL7RzjO3f+X4midKt/s+G+IPr4DGlrq+WH27eDbpUR3aYRk8EgbgGKvQFdD CEBFJi+5ZKOArmJVBSk21RHDpqyz6Vit3rjep7c1SN8s7NhVi9cjkKmMDM7KYhXkWc10lKx2 RTkFI30rkDm4U+JpdAd2+tP3tjGf9AyGGinpzE2XY1K5AQ0EVI67igEIAKiSyd0nECrgz+H5 PcFDGYQpGDMTl8MOPCKw/F3diXPuj2eql4xSbAdbUCJzk2ETif5s3twT2ER8cUTEVOaCEUY3 eOiaFgQ+nGLx4BXqqGewikPJCe+UBjFnH1m2/IFn4T9jPZkV8xlkKmDUqMK5EV9n3eQLkn5g lco+FepTtmbkSCCjd91EfThVbNYpVQ5ZjdBCXN66CKyJDMJ85HVr5rmXG/nqriTh6cv1l1Js T7AFvvPjUPknS6d+BETMhTkbGzoyS+sywEsQAgA+BMCxBH4LvUmHYhpS+W6CiZ3ZMxjO8Hgc ++w1mLeRUvda3i4/U8wDT3SWuHcB3DWlcppECLkAEQEAAYkBHwQYAQIACQUCVI67igIbDAAK CRBxXD01xc4QCZ4dB/0QrnEasxjM0PGeXK5hcZMT9Eo998alUfn5XU0RQDYdwp6/kMEXMdmT oH0F0xB3SQ8WVSXA9rrc4EBvZruWQ+5/zjVrhhfUAx12CzL4oQ9Ro2k45daYaonKTANYG22y //x8dLe2Fv1By4SKGhmzwH87uXxbTJAUxiWIi1np0z3/RDnoVyfmfbbL1DY7zf2hYXLLzsJR mSsED/1nlJ9Oq5fALdNEPgDyPUerqHxcmIub+pF0AzJoYHK5punqpqfGmqPbjxrJLPJfHVKy goMj5DlBMoYqEgpbwdUYkH6QdizJJCur4icy8GUNbisFYABeoJ91pnD4IGei3MTdvINSZI5e Message-ID: <1bff131d-d451-2597-7751-fac0269a6e37@acm.org> Date: Wed, 7 Oct 2020 19:15:49 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.12.0 MIME-Version: 1.0 In-Reply-To: <20201007145326.56850-2-mlombard@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org 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.