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RDMA/iser: Remove in_interrupt() usage

Browse source 
iser_initialize_task_headers() uses in_interrupt() to find out if it is
safe to acquire a mutex.

in_interrupt() is deprecated as it is ill defined and does not provide
what it suggests. Aside of that it covers only parts of the contexts in
which a mutex may not be acquired.

The following callchains exist:

iscsi_queuecommand() *locks* iscsi_session::frwd_lock
-> iscsi_prep_scsi_cmd_pdu()
   -> session->tt->init_task() (iscsi_iser_task_init())
      -> iser_initialize_task_headers()
-> iscsi_iser_task_xmit() (iscsi_transport::xmit_task)
  -> iscsi_iser_task_xmit_unsol_data()
    -> iser_send_data_out()
      -> iser_initialize_task_headers()

iscsi_data_xmit() *locks* iscsi_session::frwd_lock
-> iscsi_prep_mgmt_task()
   -> session->tt->init_task() (iscsi_iser_task_init())
      -> iser_initialize_task_headers()
-> iscsi_prep_scsi_cmd_pdu()
   -> session->tt->init_task() (iscsi_iser_task_init())
      -> iser_initialize_task_headers()

__iscsi_conn_send_pdu() caller has iscsi_session::frwd_lock
  -> iscsi_prep_mgmt_task()
     -> session->tt->init_task() (iscsi_iser_task_init())
        -> iser_initialize_task_headers()
  -> session->tt->xmit_task() (

The only callchain that is close to be invoked in preemptible context:
iscsi_xmitworker() worker
-> iscsi_data_xmit()
   -> iscsi_xmit_task()
      -> conn->session->tt->xmit_task() (iscsi_iser_task_xmit()

In iscsi_iser_task_xmit() there is this check:
   if (!task->sc)
      return iscsi_iser_mtask_xmit(conn, task);

so it does end up in iser_initialize_task_headers() and
iser_initialize_task_headers() relies on iscsi_task::sc == NULL.

Remove conditional locking of iser_conn::state_mutex because there is no
call chain to do so. Remove the goto label and return early now that there
is no clean up needed.

Link: https://lore.kernel.org/r/20201204174256.62xfcvudndt7oufl@linutronix.de
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Sagi Grimberg <sagi@grimberg.me>
Cc: Max Gurtovoy <maxg@nvidia.com>
Cc: Doug Ledford <dledford@redhat.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: linux-rdma@vger.kernel.org
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
This commit is contained in:
Sebastian Andrzej Siewior 2020-12-04 18:42:56 +01:00 committed by Jason Gunthorpe
parent ca991a7d14
commit 0583531bb9
1 changed files with 5 additions and 17 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

22
drivers/infiniband/ulp/iser/iscsi_iser.c
View file

@ -187,23 +187,14 @@ iser_initialize_task_headers(struct iscsi_task *task,
struct iser_device *device = iser_conn->ib_conn.device;
struct iscsi_iser_task *iser_task = task->dd_data;
u64 dma_addr;
const bool mgmt_task = !task->sc && !in_interrupt();
int ret = 0;
if (unlikely(mgmt_task))
mutex_lock(&iser_conn->state_mutex);
if (unlikely(iser_conn->state != ISER_CONN_UP)) {
ret = -ENODEV;
goto out;
}
if (unlikely(iser_conn->state != ISER_CONN_UP))
return -ENODEV;
dma_addr = ib_dma_map_single(device->ib_device, (void *)tx_desc,
ISER_HEADERS_LEN, DMA_TO_DEVICE);
if (ib_dma_mapping_error(device->ib_device, dma_addr)) {
ret = -ENOMEM;
goto out;
}
if (ib_dma_mapping_error(device->ib_device, dma_addr))
return -ENOMEM;
tx_desc->inv_wr.next = NULL;
tx_desc->reg_wr.wr.next = NULL;
@ -214,11 +205,8 @@ iser_initialize_task_headers(struct iscsi_task *task,
tx_desc->tx_sg[0].lkey = device->pd->local_dma_lkey;
iser_task->iser_conn = iser_conn;
out:
if (unlikely(mgmt_task))
mutex_unlock(&iser_conn->state_mutex);
return ret;
return 0;
}
/**