[PATCH] shpchp - bugfix: add missing serialization

Current shpchp driver might cause system panic because of lack of
serialization. It can be reproduced very easily by the following
operation.

	# cd /sys/bus/pci/slots/<slot#>
	# while true; do echo 0 > power ; echo 1 > power ; done &
	# while true; do echo 0 > power ; echo 1 > power ; done &

This patch fixes this issue by changing shpchp to get appropreate
semaphore for hot-plug operation.

Signed-off-by: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 24 insertions, 42 deletions

diff --git a/drivers/pci/hotplug/shpchp_ctrl.c b/drivers/pci/hotplug/shpchp_ctrl.c
index 802c4c48d18..1a7003d4ba9 100644
--- a/drivers/pci/hotplug/shpchp_ctrl.c
+++ b/drivers/pci/hotplug/shpchp_ctrl.c
@@ -307,15 +307,10 @@ static int board_added(struct slot *p_slot)
                         __FUNCTION__, p_slot->device,
                         ctrl->slot_device_offset, hp_slot);
 
-        /* Wait for exclusive access to hardware */
-        mutex_lock(&ctrl->crit_sect);
-
         /* Power on slot without connecting to bus */
         rc = p_slot->hpc_ops->power_on_slot(p_slot);
         if (rc) {
                 err("%s: Failed to power on slot\n", __FUNCTION__);
-                /* Done with exclusive hardware access */
-                mutex_unlock(&ctrl->crit_sect);
                 return -1;
         }
         
@@ -325,14 +320,12 @@ static int board_added(struct slot *p_slot)
                 
                 if ((rc = p_slot->hpc_ops->set_bus_speed_mode(p_slot, PCI_SPEED_33MHz))) {
                         err("%s: Issue of set bus speed mode command failed\n", __FUNCTION__);
-                        mutex_unlock(&ctrl->crit_sect);
                         return WRONG_BUS_FREQUENCY;
                 }
                 
                 /* turn on board, blink green LED, turn off Amber LED */
                 if ((rc = p_slot->hpc_ops->slot_enable(p_slot))) {
                         err("%s: Issue of Slot Enable command failed\n", __FUNCTION__);
-                        mutex_unlock(&ctrl->crit_sect);
                         return rc;
                 }
         }
@@ -346,16 +339,12 @@ static int board_added(struct slot *p_slot)
 
         if (rc  || adapter_speed == PCI_SPEED_UNKNOWN) {
                 err("%s: Can't get adapter speed or bus mode mismatch\n", __FUNCTION__);
-                /* Done with exclusive hardware access */
-                mutex_unlock(&ctrl->crit_sect);
                 return WRONG_BUS_FREQUENCY;
         }
 
         rc = p_slot->hpc_ops->get_cur_bus_speed(p_slot, &bus_speed);
         if (rc || bus_speed == PCI_SPEED_UNKNOWN) {
                 err("%s: Can't get bus operation speed\n", __FUNCTION__);
-                /* Done with exclusive hardware access */
-                mutex_unlock(&ctrl->crit_sect);
                 return WRONG_BUS_FREQUENCY;
         }
 
@@ -365,9 +354,6 @@ static int board_added(struct slot *p_slot)
                 max_bus_speed = bus_speed;
         }
 
-        /* Done with exclusive hardware access */
-        mutex_unlock(&ctrl->crit_sect);
-
         if ((rc  = p_slot->hpc_ops->get_prog_int(p_slot, &pi))) {
                 err("%s: Can't get controller programming interface, set it to 1\n", __FUNCTION__);
                 pi = 1;
@@ -744,29 +730,25 @@ static void interrupt_event_handler(struct controller *ctrl)
 int shpchp_enable_slot (struct slot *p_slot)
 {
         u8 getstatus = 0;
-        int rc;
+        int rc, retval = -ENODEV;
 
         /* Check to see if (latch closed, card present, power off) */
         mutex_lock(&p_slot->ctrl->crit_sect);
         rc = p_slot->hpc_ops->get_adapter_status(p_slot, &getstatus);
         if (rc || !getstatus) {
                 info("%s: no adapter on slot(%x)\n", __FUNCTION__, p_slot->number);
-                mutex_unlock(&p_slot->ctrl->crit_sect);
-                return -ENODEV;
+                goto out;
         }
         rc = p_slot->hpc_ops->get_latch_status(p_slot, &getstatus);
         if (rc || getstatus) {
                 info("%s: latch open on slot(%x)\n", __FUNCTION__, p_slot->number);
-                mutex_unlock(&p_slot->ctrl->crit_sect);
-                return -ENODEV;
+                goto out;
         }
         rc = p_slot->hpc_ops->get_power_status(p_slot, &getstatus);
         if (rc || getstatus) {
                 info("%s: already enabled on slot(%x)\n", __FUNCTION__, p_slot->number);
-                mutex_unlock(&p_slot->ctrl->crit_sect);
-                return -ENODEV;
+                goto out;
         }
-        mutex_unlock(&p_slot->ctrl->crit_sect);
 
         p_slot->is_a_board = 1;
 
@@ -781,27 +763,29 @@ int shpchp_enable_slot (struct slot *p_slot)
              && p_slot->ctrl->num_slots == 1) {
                 /* handle amd pogo errata; this must be done before enable  */
                 amd_pogo_errata_save_misc_reg(p_slot);
-                rc = board_added(p_slot);
+                retval = board_added(p_slot);
                 /* handle amd pogo errata; this must be done after enable  */
                 amd_pogo_errata_restore_misc_reg(p_slot);
         } else
-                rc = board_added(p_slot);
+                retval = board_added(p_slot);
 
-        if (rc) {
+        if (retval) {
                 p_slot->hpc_ops->get_adapter_status(p_slot,
                                 &(p_slot->presence_save));
                 p_slot->hpc_ops->get_latch_status(p_slot, &getstatus);
         }
 
         update_slot_info(p_slot);
-        return rc;
+ out:
+        mutex_unlock(&p_slot->ctrl->crit_sect);
+        return retval;
 }
 
 
 int shpchp_disable_slot (struct slot *p_slot)
 {
         u8 getstatus = 0;
-        int ret = 0;
+        int rc, retval = -ENODEV;
 
         if (!p_slot->ctrl)
                 return -ENODEV;
@@ -809,28 +793,26 @@ int shpchp_disable_slot (struct slot *p_slot)
         /* Check to see if (latch closed, card present, power on) */
         mutex_lock(&p_slot->ctrl->crit_sect);
 
-        ret = p_slot->hpc_ops->get_adapter_status(p_slot, &getstatus);
-        if (ret || !getstatus) {
+        rc = p_slot->hpc_ops->get_adapter_status(p_slot, &getstatus);
+        if (rc || !getstatus) {
                 info("%s: no adapter on slot(%x)\n", __FUNCTION__, p_slot->number);
-                mutex_unlock(&p_slot->ctrl->crit_sect);
-                return -ENODEV;
+                goto out;
         }
-        ret = p_slot->hpc_ops->get_latch_status(p_slot, &getstatus);
-        if (ret || getstatus) {
+        rc = p_slot->hpc_ops->get_latch_status(p_slot, &getstatus);
+        if (rc || getstatus) {
                 info("%s: latch open on slot(%x)\n", __FUNCTION__, p_slot->number);
-                mutex_unlock(&p_slot->ctrl->crit_sect);
-                return -ENODEV;
+                goto out;
         }
-        ret = p_slot->hpc_ops->get_power_status(p_slot, &getstatus);
-        if (ret || !getstatus) {
+        rc = p_slot->hpc_ops->get_power_status(p_slot, &getstatus);
+        if (rc || !getstatus) {
                 info("%s: already disabled slot(%x)\n", __FUNCTION__, p_slot->number);
-                mutex_unlock(&p_slot->ctrl->crit_sect);
-                return -ENODEV;
+                goto out;
         }
-        mutex_unlock(&p_slot->ctrl->crit_sect);
 
-        ret = remove_board(p_slot);
+        retval = remove_board(p_slot);
         update_slot_info(p_slot);
-        return ret;
+ out:
+        mutex_unlock(&p_slot->ctrl->crit_sect);
+        return retval;
 }