[PATCH 4.9 074/108] bnxt_en: Fix bnxt_reset() in the slow path task.

Greg Kroah-Hartman
2017-06-15T18:10:55Z

From: Michael Chan <michael.chan@broadcom.com>

[ Upstream commit a551ee94ea723b4af9b827c7460f108bc13425ee ]

In bnxt_sp_task(), we set a bit BNXT_STATE_IN_SP_TASK so that bnxt_close()
will synchronize and wait for bnxt_sp_task() to finish. Some functions
in bnxt_sp_task() require us to clear BNXT_STATE_IN_SP_TASK and then
acquire rtnl_lock() to prevent race conditions.

There are some bugs related to this logic. This patch refactors the code
to have common bnxt_rtnl_lock_sp() and bnxt_rtnl_unlock_sp() to handle
the RTNL and the clearing/setting of the bit. Multiple functions will
need the same logic. We also need to move bnxt_reset() to the end of
bnxt_sp_task(). Functions that clear BNXT_STATE_IN_SP_TASK must be the
last functions to be called in bnxt_sp_task(). The common scheme will
handle the condition properly.

Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/net/ethernet/broadcom/bnxt/bnxt.c | 38 +++++++++++++++++++-----------
1 file changed, 25 insertions(+), 13 deletions(-)

--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
@@ -6080,23 +6080,32 @@ bnxt_restart_timer:
mod_timer(&bp->timer, jiffies + bp->current_interval);
}

-/* Only called from bnxt_sp_task() */
-static void bnxt_reset(struct bnxt *bp, bool silent)
+static void bnxt_rtnl_lock_sp(struct bnxt *bp)
{
- /* bnxt_reset_task() calls bnxt_close_nic() which waits
- * for BNXT_STATE_IN_SP_TASK to clear.
- * If there is a parallel dev_close(), bnxt_close() may be holding
+ /* We are called from bnxt_sp_task which has BNXT_STATE_IN_SP_TASK
+ * set. If the device is being closed, bnxt_close() may be holding
* rtnl() and waiting for BNXT_STATE_IN_SP_TASK to clear. So we
* must clear BNXT_STATE_IN_SP_TASK before holding rtnl().
*/
clear_bit(BNXT_STATE_IN_SP_TASK, &bp->state);
rtnl_lock();
- if (test_bit(BNXT_STATE_OPEN, &bp->state))
- bnxt_reset_task(bp, silent);
+}
+
+static void bnxt_rtnl_unlock_sp(struct bnxt *bp)
+{
set_bit(BNXT_STATE_IN_SP_TASK, &bp->state);
rtnl_unlock();
}

+/* Only called from bnxt_sp_task() */
+static void bnxt_reset(struct bnxt *bp, bool silent)
+{
+ bnxt_rtnl_lock_sp(bp);
+ if (test_bit(BNXT_STATE_OPEN, &bp->state))
+ bnxt_reset_task(bp, silent);
+ bnxt_rtnl_unlock_sp(bp);
+}
+
static void bnxt_cfg_ntp_filters(struct bnxt *);

static void bnxt_sp_task(struct work_struct *work)
@@ -6142,18 +6151,21 @@ static void bnxt_sp_task(struct work_str
bnxt_hwrm_tunnel_dst_port_free(
bp, TUNNEL_DST_PORT_FREE_REQ_TUNNEL_TYPE_GENEVE);
}
- if (test_and_clear_bit(BNXT_RESET_TASK_SP_EVENT, &bp->sp_event))
- bnxt_reset(bp, false);
-
- if (test_and_clear_bit(BNXT_RESET_TASK_SILENT_SP_EVENT, &bp->sp_event))
- bnxt_reset(bp, true);
-
if (test_and_clear_bit(BNXT_HWRM_PORT_MODULE_SP_EVENT, &bp->sp_event))
bnxt_get_port_module_status(bp);

if (test_and_clear_bit(BNXT_PERIODIC_STATS_SP_EVENT, &bp->sp_event))
bnxt_hwrm_port_qstats(bp);

+ /* These functions below will clear BNXT_STATE_IN_SP_TASK. They
+ * must be the last functions to be called before exiting.
+ */
+ if (test_and_clear_bit(BNXT_RESET_TASK_SP_EVENT, &bp->sp_event))
+ bnxt_reset(bp, false);
+
+ if (test_and_clear_bit(BNXT_RESET_TASK_SILENT_SP_EVENT, &bp->sp_event))
+ bnxt_reset(bp, true);
+
smp_mb__before_atomic();
clear_bit(BNXT_STATE_IN_SP_TASK, &bp->state);
}