7 files changed, 131 insertions, 50 deletions

diff --git a/drivers/pci/access.c b/drivers/pci/access.c
index fdaa42aac7c6..0c4c71712dfc 100644
--- a/drivers/pci/access.c
+++ b/drivers/pci/access.c
@@ -127,20 +127,20 @@ EXPORT_SYMBOL(pci_write_vpd);
  * We have a bit per device to indicate it's blocked and a global wait queue
  * for callers to sleep on until devices are unblocked.
  */
-static DECLARE_WAIT_QUEUE_HEAD(pci_ucfg_wait);
+static DECLARE_WAIT_QUEUE_HEAD(pci_cfg_wait);
 
-static noinline void pci_wait_ucfg(struct pci_dev *dev)
+static noinline void pci_wait_cfg(struct pci_dev *dev)
 {
         DECLARE_WAITQUEUE(wait, current);
 
-        __add_wait_queue(&pci_ucfg_wait, &wait);
+        __add_wait_queue(&pci_cfg_wait, &wait);
         do {
                 set_current_state(TASK_UNINTERRUPTIBLE);
                 raw_spin_unlock_irq(&pci_lock);
                 schedule();
                 raw_spin_lock_irq(&pci_lock);
-        } while (dev->block_ucfg_access);
-        __remove_wait_queue(&pci_ucfg_wait, &wait);
+        } while (dev->block_cfg_access);
+        __remove_wait_queue(&pci_cfg_wait, &wait);
 }
 
 /* Returns 0 on success, negative values indicate error. */
@@ -153,7 +153,8 @@ int pci_user_read_config_##size						\
         if (PCI_##size##_BAD)                                           \
                 return -EINVAL;                                         \
         raw_spin_lock_irq(&pci_lock);                           \
-        if (unlikely(dev->block_ucfg_access)) pci_wait_ucfg(dev);       \
+        if (unlikely(dev->block_cfg_access))                            \
+                pci_wait_cfg(dev);                                      \
         ret = dev->bus->ops->read(dev->bus, dev->devfn,                 \
                                         pos, sizeof(type), &data);      \
         raw_spin_unlock_irq(&pci_lock);                         \
@@ -172,7 +173,8 @@ int pci_user_write_config_##size					\
         if (PCI_##size##_BAD)                                           \
                 return -EINVAL;                                         \
         raw_spin_lock_irq(&pci_lock);                           \
-        if (unlikely(dev->block_ucfg_access)) pci_wait_ucfg(dev);       \
+        if (unlikely(dev->block_cfg_access))                            \
+                pci_wait_cfg(dev);                                      \
         ret = dev->bus->ops->write(dev->bus, dev->devfn,                \
                                         pos, sizeof(type), val);        \
         raw_spin_unlock_irq(&pci_lock);                         \
@@ -401,36 +403,56 @@ int pci_vpd_truncate(struct pci_dev *dev, size_t size)
 EXPORT_SYMBOL(pci_vpd_truncate);
 
 /**
- * pci_block_user_cfg_access - Block userspace PCI config reads/writes
+ * pci_cfg_access_lock - Lock PCI config reads/writes
  * @dev:        pci device struct
  *
- * When user access is blocked, any reads or writes to config space will
- * sleep until access is unblocked again.  We don't allow nesting of
- * block/unblock calls.
+ * When access is locked, any userspace reads or writes to config
+ * space and concurrent lock requests will sleep until access is
+ * allowed via pci_cfg_access_unlocked again.
  */
-void pci_block_user_cfg_access(struct pci_dev *dev)
+void pci_cfg_access_lock(struct pci_dev *dev)
+{
+        might_sleep();
+
+        raw_spin_lock_irq(&pci_lock);
+        if (dev->block_cfg_access)
+                pci_wait_cfg(dev);
+        dev->block_cfg_access = 1;
+        raw_spin_unlock_irq(&pci_lock);
+}
+EXPORT_SYMBOL_GPL(pci_cfg_access_lock);
+
+/**
+ * pci_cfg_access_trylock - try to lock PCI config reads/writes
+ * @dev:        pci device struct
+ *
+ * Same as pci_cfg_access_lock, but will return 0 if access is
+ * already locked, 1 otherwise. This function can be used from
+ * atomic contexts.
+ */
+bool pci_cfg_access_trylock(struct pci_dev *dev)
 {
         unsigned long flags;
-        int was_blocked;
+        bool locked = true;
 
         raw_spin_lock_irqsave(&pci_lock, flags);
-        was_blocked = dev->block_ucfg_access;
-        dev->block_ucfg_access = 1;
+        if (dev->block_cfg_access)
+                locked = false;
+        else
+                dev->block_cfg_access = 1;
         raw_spin_unlock_irqrestore(&pci_lock, flags);
 
-        /* If we BUG() inside the pci_lock, we're guaranteed to hose
-         * the machine */
-        BUG_ON(was_blocked);
+        return locked;
 }
-EXPORT_SYMBOL_GPL(pci_block_user_cfg_access);
+EXPORT_SYMBOL_GPL(pci_cfg_access_trylock);
 
 /**
- * pci_unblock_user_cfg_access - Unblock userspace PCI config reads/writes
+ * pci_cfg_access_unlock - Unlock PCI config reads/writes
  * @dev:        pci device struct
  *
- * This function allows userspace PCI config accesses to resume.
+ * This function allows PCI config accesses to resume.
  */
-void pci_unblock_user_cfg_access(struct pci_dev *dev)
+void pci_cfg_access_unlock(struct pci_dev *dev)
 {
         unsigned long flags;
 
@@ -438,10 +460,10 @@ void pci_unblock_user_cfg_access(struct pci_dev *dev)
 
         /* This indicates a problem in the caller, but we don't need
          * to kill them, unlike a double-block above. */
-        WARN_ON(!dev->block_ucfg_access);
+        WARN_ON(!dev->block_cfg_access);
 
-        dev->block_ucfg_access = 0;
-        wake_up_all(&pci_ucfg_wait);
+        dev->block_cfg_access = 0;
+        wake_up_all(&pci_cfg_wait);
         raw_spin_unlock_irqrestore(&pci_lock, flags);
 }
-EXPORT_SYMBOL_GPL(pci_unblock_user_cfg_access);
+EXPORT_SYMBOL_GPL(pci_cfg_access_unlock);
diff --git a/drivers/pci/iov.c b/drivers/pci/iov.c
index 1969a3ee3058..6a4d70386a3d 100644
--- a/drivers/pci/iov.c
+++ b/drivers/pci/iov.c
@@ -348,10 +348,10 @@ static int sriov_enable(struct pci_dev *dev, int nr_virtfn)
         }
 
         iov->ctrl |= PCI_SRIOV_CTRL_VFE | PCI_SRIOV_CTRL_MSE;
-        pci_block_user_cfg_access(dev);
+        pci_cfg_access_lock(dev);
         pci_write_config_word(dev, iov->pos + PCI_SRIOV_CTRL, iov->ctrl);
         msleep(100);
-        pci_unblock_user_cfg_access(dev);
+        pci_cfg_access_unlock(dev);
 
         iov->initial = initial;
         if (nr_virtfn < initial)
@@ -379,10 +379,10 @@ failed:
                 virtfn_remove(dev, j, 0);
 
         iov->ctrl &= ~(PCI_SRIOV_CTRL_VFE | PCI_SRIOV_CTRL_MSE);
-        pci_block_user_cfg_access(dev);
+        pci_cfg_access_lock(dev);
         pci_write_config_word(dev, iov->pos + PCI_SRIOV_CTRL, iov->ctrl);
         ssleep(1);
-        pci_unblock_user_cfg_access(dev);
+        pci_cfg_access_unlock(dev);
 
         if (iov->link != dev->devfn)
                 sysfs_remove_link(&dev->dev.kobj, "dep_link");
@@ -405,10 +405,10 @@ static void sriov_disable(struct pci_dev *dev)
                 virtfn_remove(dev, i, 0);
 
         iov->ctrl &= ~(PCI_SRIOV_CTRL_VFE | PCI_SRIOV_CTRL_MSE);
-        pci_block_user_cfg_access(dev);
+        pci_cfg_access_lock(dev);
         pci_write_config_word(dev, iov->pos + PCI_SRIOV_CTRL, iov->ctrl);
         ssleep(1);
-        pci_unblock_user_cfg_access(dev);
+        pci_cfg_access_unlock(dev);
 
         if (iov->link != dev->devfn)
                 sysfs_remove_link(&dev->dev.kobj, "dep_link");
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 6d4a5319148d..c3cca7cdc6e5 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -2965,7 +2965,7 @@ static int pci_dev_reset(struct pci_dev *dev, int probe)
         might_sleep();
 
         if (!probe) {
-                pci_block_user_cfg_access(dev);
+                pci_cfg_access_lock(dev);
                 /* block PM suspend, driver probe, etc. */
                 device_lock(&dev->dev);
         }
@@ -2990,7 +2990,7 @@ static int pci_dev_reset(struct pci_dev *dev, int probe)
 done:
         if (!probe) {
                 device_unlock(&dev->dev);
-                pci_unblock_user_cfg_access(dev);
+                pci_cfg_access_unlock(dev);
         }
 
         return rc;
diff --git a/drivers/scsi/ipr.c b/drivers/scsi/ipr.c
index fd860d952b28..67b169b7a5be 100644
--- a/drivers/scsi/ipr.c
+++ b/drivers/scsi/ipr.c
@@ -7638,8 +7638,12 @@ static int ipr_reset_restore_cfg_space(struct ipr_cmnd *ipr_cmd)
  **/
 static int ipr_reset_bist_done(struct ipr_cmnd *ipr_cmd)
 {
+        struct ipr_ioa_cfg *ioa_cfg = ipr_cmd->ioa_cfg;
+
         ENTER;
-        pci_unblock_user_cfg_access(ipr_cmd->ioa_cfg->pdev);
+        if (ioa_cfg->cfg_locked)
+                pci_cfg_access_unlock(ioa_cfg->pdev);
+        ioa_cfg->cfg_locked = 0;
         ipr_cmd->job_step = ipr_reset_restore_cfg_space;
         LEAVE;
         return IPR_RC_JOB_CONTINUE;
@@ -7660,8 +7664,6 @@ static int ipr_reset_start_bist(struct ipr_cmnd *ipr_cmd)
         int rc = PCIBIOS_SUCCESSFUL;
 
         ENTER;
-        pci_block_user_cfg_access(ioa_cfg->pdev);
-
         if (ioa_cfg->ipr_chip->bist_method == IPR_MMIO)
                 writel(IPR_UPROCI_SIS64_START_BIST,
                        ioa_cfg->regs.set_uproc_interrupt_reg32);
@@ -7673,7 +7675,9 @@ static int ipr_reset_start_bist(struct ipr_cmnd *ipr_cmd)
                 ipr_reset_start_timer(ipr_cmd, IPR_WAIT_FOR_BIST_TIMEOUT);
                 rc = IPR_RC_JOB_RETURN;
         } else {
-                pci_unblock_user_cfg_access(ipr_cmd->ioa_cfg->pdev);
+                if (ioa_cfg->cfg_locked)
+                        pci_cfg_access_unlock(ipr_cmd->ioa_cfg->pdev);
+                ioa_cfg->cfg_locked = 0;
                 ipr_cmd->s.ioasa.hdr.ioasc = cpu_to_be32(IPR_IOASC_PCI_ACCESS_ERROR);
                 rc = IPR_RC_JOB_CONTINUE;
         }
@@ -7716,7 +7720,6 @@ static int ipr_reset_slot_reset(struct ipr_cmnd *ipr_cmd)
         struct pci_dev *pdev = ioa_cfg->pdev;
 
         ENTER;
-        pci_block_user_cfg_access(pdev);
         pci_set_pcie_reset_state(pdev, pcie_warm_reset);
         ipr_cmd->job_step = ipr_reset_slot_reset_done;
         ipr_reset_start_timer(ipr_cmd, IPR_PCI_RESET_TIMEOUT);
@@ -7725,6 +7728,56 @@ static int ipr_reset_slot_reset(struct ipr_cmnd *ipr_cmd)
 }
 
 /**
+ * ipr_reset_block_config_access_wait - Wait for permission to block config access
+ * @ipr_cmd:    ipr command struct
+ *
+ * Description: This attempts to block config access to the IOA.
+ *
+ * Return value:
+ *      IPR_RC_JOB_CONTINUE / IPR_RC_JOB_RETURN
+ **/
+static int ipr_reset_block_config_access_wait(struct ipr_cmnd *ipr_cmd)
+{
+        struct ipr_ioa_cfg *ioa_cfg = ipr_cmd->ioa_cfg;
+        int rc = IPR_RC_JOB_CONTINUE;
+
+        if (pci_cfg_access_trylock(ioa_cfg->pdev)) {
+                ioa_cfg->cfg_locked = 1;
+                ipr_cmd->job_step = ioa_cfg->reset;
+        } else {
+                if (ipr_cmd->u.time_left) {
+                        rc = IPR_RC_JOB_RETURN;
+                        ipr_cmd->u.time_left -= IPR_CHECK_FOR_RESET_TIMEOUT;
+                        ipr_reset_start_timer(ipr_cmd,
+                                              IPR_CHECK_FOR_RESET_TIMEOUT);
+                } else {
+                        ipr_cmd->job_step = ioa_cfg->reset;
+                        dev_err(&ioa_cfg->pdev->dev,
+                                "Timed out waiting to lock config access. Resetting anyway.\n");
+                }
+        }
+
+        return rc;
+}
+
+/**
+ * ipr_reset_block_config_access - Block config access to the IOA
+ * @ipr_cmd:    ipr command struct
+ *
+ * Description: This attempts to block config access to the IOA
+ *
+ * Return value:
+ *      IPR_RC_JOB_CONTINUE
+ **/
+static int ipr_reset_block_config_access(struct ipr_cmnd *ipr_cmd)
+{
+        ipr_cmd->ioa_cfg->cfg_locked = 0;
+        ipr_cmd->job_step = ipr_reset_block_config_access_wait;
+        ipr_cmd->u.time_left = IPR_WAIT_FOR_RESET_TIMEOUT;
+        return IPR_RC_JOB_CONTINUE;
+}
+
+/**
  * ipr_reset_allowed - Query whether or not IOA can be reset
  * @ioa_cfg:    ioa config struct
  *
@@ -7763,7 +7816,7 @@ static int ipr_reset_wait_to_start_bist(struct ipr_cmnd *ipr_cmd)
                 ipr_cmd->u.time_left -= IPR_CHECK_FOR_RESET_TIMEOUT;
                 ipr_reset_start_timer(ipr_cmd, IPR_CHECK_FOR_RESET_TIMEOUT);
         } else {
-                ipr_cmd->job_step = ioa_cfg->reset;
+                ipr_cmd->job_step = ipr_reset_block_config_access;
                 rc = IPR_RC_JOB_CONTINUE;
         }
 
@@ -7796,7 +7849,7 @@ static int ipr_reset_alert(struct ipr_cmnd *ipr_cmd)
                 writel(IPR_UPROCI_RESET_ALERT, ioa_cfg->regs.set_uproc_interrupt_reg32);
                 ipr_cmd->job_step = ipr_reset_wait_to_start_bist;
         } else {
-                ipr_cmd->job_step = ioa_cfg->reset;
+                ipr_cmd->job_step = ipr_reset_block_config_access;
         }
 
         ipr_cmd->u.time_left = IPR_WAIT_FOR_RESET_TIMEOUT;
diff --git a/drivers/scsi/ipr.h b/drivers/scsi/ipr.h
index ac84736c1b9c..b13f9cc12279 100644
--- a/drivers/scsi/ipr.h
+++ b/drivers/scsi/ipr.h
@@ -1387,6 +1387,7 @@ struct ipr_ioa_cfg {
         u8 msi_received:1;
         u8 sis64:1;
         u8 dump_timeout:1;
+        u8 cfg_locked:1;
 
         u8 revid;
 
diff --git a/drivers/uio/uio_pci_generic.c b/drivers/uio/uio_pci_generic.c
index 02bd47bdee1c..56d00c6258f0 100644
--- a/drivers/uio/uio_pci_generic.c
+++ b/drivers/uio/uio_pci_generic.c
@@ -55,7 +55,8 @@ static irqreturn_t irqhandler(int irq, struct uio_info *info)
         BUILD_BUG_ON(PCI_COMMAND % 4);
         BUILD_BUG_ON(PCI_COMMAND + 2 != PCI_STATUS);
 
-        pci_block_user_cfg_access(pdev);
+        if (!pci_cfg_access_trylock(pdev))
+                goto error;
 
         /* Read both command and status registers in a single 32-bit operation.
          * Note: we could cache the value for command and move the status read
@@ -79,7 +80,7 @@ static irqreturn_t irqhandler(int irq, struct uio_info *info)
         ret = IRQ_HANDLED;
 done:
 
-        pci_unblock_user_cfg_access(pdev);
+        pci_cfg_access_lock(pdev);
         return ret;
 }
 
@@ -91,7 +92,7 @@ static int __devinit verify_pci_2_3(struct pci_dev *pdev)
         u16 orig, new;
         int err = 0;
 
-        pci_block_user_cfg_access(pdev);
+        pci_cfg_access_lock(pdev);
         pci_read_config_word(pdev, PCI_COMMAND, &orig);
         pci_write_config_word(pdev, PCI_COMMAND,
                               orig ^ PCI_COMMAND_INTX_DISABLE);
@@ -114,7 +115,7 @@ static int __devinit verify_pci_2_3(struct pci_dev *pdev)
         /* Now restore the original value. */
         pci_write_config_word(pdev, PCI_COMMAND, orig);
 err:
-        pci_unblock_user_cfg_access(pdev);
+        pci_cfg_access_unlock(pdev);
         return err;
 }
 
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 84225c756bd1..72401596b2a8 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -308,7 +308,7 @@ struct pci_dev {
         unsigned int    is_added:1;
         unsigned int    is_busmaster:1; /* device is busmaster */
         unsigned int    no_msi:1;       /* device may not use msi */
-        unsigned int    block_ucfg_access:1;    /* userspace config space access is blocked */
+        unsigned int    block_cfg_access:1;     /* config space access is blocked */
         unsigned int    broken_parity_status:1; /* Device generates false positive parity */
         unsigned int    irq_reroute_variant:2;  /* device needs IRQ rerouting variant */
         unsigned int    msi_enabled:1;
@@ -1085,8 +1085,9 @@ int  ht_create_irq(struct pci_dev *dev, int idx);
 void ht_destroy_irq(unsigned int irq);
 #endif /* CONFIG_HT_IRQ */
 
-extern void pci_block_user_cfg_access(struct pci_dev *dev);
-extern void pci_unblock_user_cfg_access(struct pci_dev *dev);
+extern void pci_cfg_access_lock(struct pci_dev *dev);
+extern bool pci_cfg_access_trylock(struct pci_dev *dev);
+extern void pci_cfg_access_unlock(struct pci_dev *dev);
 
 /*
  * PCI domain support.  Sometimes called PCI segment (eg by ACPI),
@@ -1283,10 +1284,13 @@ static inline void pci_release_regions(struct pci_dev *dev)
 
 #define pci_dma_burst_advice(pdev, strat, strategy_parameter) do { } while (0)
 
-static inline void pci_block_user_cfg_access(struct pci_dev *dev)
+static inline void pci_block_cfg_access(struct pci_dev *dev)
 { }
 
-static inline void pci_unblock_user_cfg_access(struct pci_dev *dev)
+static inline int pci_block_cfg_access_in_atomic(struct pci_dev *dev)
+{ return 0; }
+
+static inline void pci_unblock_cfg_access(struct pci_dev *dev)
 { }
 
 static inline struct pci_bus *pci_find_next_bus(const struct pci_bus *from)