sfc: Allow resets to be upgraded; use atomic ops for safety

Currently an attempt to schedule any reset is ignored if a reset
is already pending.  This ignores the relative scopes - if the
requested reset is greater in scope then the scheduled reset should
be upgraded accordingly.

There are also some race conditions which could lead to a reset
request being lost.  Deal with them by using atomic operations on a
bitmask.  This also makes tests on reset_pending easier to get right.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>

diff --git a/drivers/net/sfc/efx.c b/drivers/net/sfc/efx.c
index c914729..9b4cfdb 100644 (file)
--- a/drivers/net/sfc/efx.c
+++ b/drivers/net/sfc/efx.c
@@ -229,8 +229,7 @@ static int efx_process_channel(struct efx_channel *channel, int budget)
        struct efx_nic *efx = channel->efx;
        int spent;
 
-       if (unlikely(efx->reset_pending != RESET_TYPE_NONE ||
-                    !channel->enabled))
+       if (unlikely(efx->reset_pending || !channel->enabled))
                return 0;
 
        spent = efx_nic_process_eventq(channel, budget);
@@ -1461,7 +1460,7 @@ static void efx_start_all(struct efx_nic *efx)
         * reset_pending [modified from an atomic context], we instead guarantee
         * that efx_mcdi_mode_poll() isn't reverted erroneously */
        efx_mcdi_mode_event(efx);
-       if (efx->reset_pending != RESET_TYPE_NONE)
+       if (efx->reset_pending)
                efx_mcdi_mode_poll(efx);
 
        /* Start the hardware monitor if there is one. Otherwise (we're link
@@ -2118,8 +2117,10 @@ int efx_reset(struct efx_nic *efx, enum reset_type method)
                goto out;
        }
 
-       /* Allow resets to be rescheduled. */
-       efx->reset_pending = RESET_TYPE_NONE;
+       /* Clear flags for the scopes we covered.  We assume the NIC and
+        * driver are now quiescent so that there is no race here.
+        */
+       efx->reset_pending &= -(1 << (method + 1));
 
        /* Reinitialise bus-mastering, which may have been turned off before
         * the reset was scheduled. This is still appropriate, even in the
@@ -2154,12 +2155,13 @@ out:
 static void efx_reset_work(struct work_struct *data)
 {
        struct efx_nic *efx = container_of(data, struct efx_nic, reset_work);
+       unsigned long pending = ACCESS_ONCE(efx->reset_pending);
 
-       if (efx->reset_pending == RESET_TYPE_NONE)
+       if (!pending)
                return;
 
        /* If we're not RUNNING then don't reset. Leave the reset_pending
-        * flag set so that efx_pci_probe_main will be retried */
+        * flags set so that efx_pci_probe_main will be retried */
        if (efx->state != STATE_RUNNING) {
                netif_info(efx, drv, efx->net_dev,
                           "scheduled reset quenched. NIC not RUNNING\n");
@@ -2167,7 +2169,7 @@ static void efx_reset_work(struct work_struct *data)
        }
 
        rtnl_lock();
-       (void)efx_reset(efx, efx->reset_pending);
+       (void)efx_reset(efx, fls(pending) - 1);
        rtnl_unlock();
 }
 
@@ -2175,12 +2177,6 @@ void efx_schedule_reset(struct efx_nic *efx, enum reset_type type)
 {
        enum reset_type method;
 
-       if (efx->reset_pending != RESET_TYPE_NONE) {
-               netif_info(efx, drv, efx->net_dev,
-                          "quenching already scheduled reset\n");
-               return;
-       }
-
        switch (type) {
        case RESET_TYPE_INVISIBLE:
        case RESET_TYPE_ALL:
@@ -2208,7 +2204,7 @@ void efx_schedule_reset(struct efx_nic *efx, enum reset_type type)
                netif_dbg(efx, drv, efx->net_dev, "scheduling %s reset\n",
                          RESET_TYPE(method));
 
-       efx->reset_pending = method;
+       set_bit(method, &efx->reset_pending);
 
        /* efx_process_channel() will no longer read events once a
         * reset is scheduled. So switch back to poll'd MCDI completions. */
@@ -2288,7 +2284,6 @@ static int efx_init_struct(struct efx_nic *efx, const struct efx_nic_type *type,
        efx->pci_dev = pci_dev;
        efx->msg_enable = debug;
        efx->state = STATE_INIT;
-       efx->reset_pending = RESET_TYPE_NONE;
        strlcpy(efx->name, pci_name(pci_dev), sizeof(efx->name));
 
        efx->net_dev = net_dev;
@@ -2510,7 +2505,7 @@ static int __devinit efx_pci_probe(struct pci_dev *pci_dev,
                cancel_work_sync(&efx->reset_work);
 
                if (rc == 0) {
-                       if (efx->reset_pending != RESET_TYPE_NONE) {
+                       if (efx->reset_pending) {
                                /* If there was a scheduled reset during
                                 * probe, the NIC is probably hosed anyway */
                                efx_pci_remove_main(efx);
@@ -2521,11 +2516,12 @@ static int __devinit efx_pci_probe(struct pci_dev *pci_dev,
                }
 
                /* Retry if a recoverably reset event has been scheduled */
-               if ((efx->reset_pending != RESET_TYPE_INVISIBLE) &&
-                   (efx->reset_pending != RESET_TYPE_ALL))
+               if (efx->reset_pending &
+                   ~(1 << RESET_TYPE_INVISIBLE | 1 << RESET_TYPE_ALL) ||
+                   !efx->reset_pending)
                        goto fail3;
 
-               efx->reset_pending = RESET_TYPE_NONE;
+               efx->reset_pending = 0;
        }
 
        if (rc) {
@@ -2609,7 +2605,7 @@ static int efx_pm_poweroff(struct device *dev)
 
        efx->type->fini(efx);
 
-       efx->reset_pending = RESET_TYPE_NONE;
+       efx->reset_pending = 0;
 
        pci_save_state(pci_dev);
        return pci_set_power_state(pci_dev, PCI_D3hot);

diff --git a/drivers/net/sfc/enum.h b/drivers/net/sfc/enum.h
index 384cfe3..d725a8f 100644 (file)
--- a/drivers/net/sfc/enum.h
+++ b/drivers/net/sfc/enum.h
@@ -134,6 +134,8 @@ enum efx_loopback_mode {
  * other valuesspecify reasons, which efx_schedule_reset() will choose
  * a method for.
  *
+ * Reset methods are numbered in order of increasing scope.
+ *
  * @RESET_TYPE_INVISIBLE: don't reset the PHYs or interrupts
  * @RESET_TYPE_ALL: reset everything but PCI core blocks
  * @RESET_TYPE_WORLD: reset everything, save & restore PCI config
@@ -147,7 +149,6 @@ enum efx_loopback_mode {
  * @RESET_TYPE_MC_FAILURE: MC reboot/assertion
  */
 enum reset_type {
-       RESET_TYPE_NONE = -1,
        RESET_TYPE_INVISIBLE = 0,
        RESET_TYPE_ALL = 1,
        RESET_TYPE_WORLD = 2,

diff --git a/drivers/net/sfc/falcon.c b/drivers/net/sfc/falcon.c
index 60176e8..a4c7830 100644 (file)
--- a/drivers/net/sfc/falcon.c
+++ b/drivers/net/sfc/falcon.c
@@ -536,7 +536,7 @@ void falcon_reconfigure_mac_wrapper(struct efx_nic *efx)
        efx_oword_t reg;
        int link_speed, isolate;
 
-       isolate = (efx->reset_pending != RESET_TYPE_NONE);
+       isolate = !!ACCESS_ONCE(efx->reset_pending);
 
        switch (link_state->speed) {
        case 10000: link_speed = 3; break;

diff --git a/drivers/net/sfc/net_driver.h b/drivers/net/sfc/net_driver.h
index e8d5f03..c422eb2 100644 (file)
--- a/drivers/net/sfc/net_driver.h
+++ b/drivers/net/sfc/net_driver.h
@@ -645,7 +645,7 @@ struct efx_filter_state;
  * @irq_rx_moderation: IRQ moderation time for RX event queues
  * @msg_enable: Log message enable flags
  * @state: Device state flag. Serialised by the rtnl_lock.
- * @reset_pending: Pending reset method (normally RESET_TYPE_NONE)
+ * @reset_pending: Bitmask for pending resets
  * @tx_queue: TX DMA queues
  * @rx_queue: RX DMA queues
  * @channel: Channels
@@ -728,7 +728,7 @@ struct efx_nic {
        u32 msg_enable;
 
        enum nic_state state;
-       enum reset_type reset_pending;
+       unsigned long reset_pending;
 
        struct efx_channel *channel[EFX_MAX_CHANNELS];
        char channel_name[EFX_MAX_CHANNELS][IFNAMSIZ + 6];