PCI: handle PCI state saving with interrupts disabled

Since interrupts will soon be disabled at PCI resume time, we need to
pre-allocate memory to save/restore PCI config space (or use GFP_ATOMIC,
but this is safer).

Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: "Rafael J. Wysocki" <rjw@sisk.pl>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

1 files changed, 51 insertions, 22 deletions

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 47663dc0daf7..3222f9022707 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -640,19 +640,14 @@ static int pci_save_pcie_state(struct pci_dev *dev)
         int pos, i = 0;
         struct pci_cap_saved_state *save_state;
         u16 *cap;
-        int found = 0;
 
         pos = pci_find_capability(dev, PCI_CAP_ID_EXP);
         if (pos <= 0)
                 return 0;
 
         save_state = pci_find_saved_cap(dev, PCI_CAP_ID_EXP);
-        if (!save_state)
-                save_state = kzalloc(sizeof(*save_state) + sizeof(u16) * 4, GFP_KERNEL);
-        else
-                found = 1;
         if (!save_state) {
-                dev_err(&dev->dev, "out of memory in pci_save_pcie_state\n");
+                dev_err(&dev->dev, "buffer not found in %s\n", __FUNCTION__);
                 return -ENOMEM;
         }
         cap = (u16 *)&save_state->data[0];
@@ -661,9 +656,7 @@ static int pci_save_pcie_state(struct pci_dev *dev)
         pci_read_config_word(dev, pos + PCI_EXP_LNKCTL, &cap[i++]);
         pci_read_config_word(dev, pos + PCI_EXP_SLTCTL, &cap[i++]);
         pci_read_config_word(dev, pos + PCI_EXP_RTCTL, &cap[i++]);
-        save_state->cap_nr = PCI_CAP_ID_EXP;
-        if (!found)
-                pci_add_saved_cap(dev, save_state);
+
         return 0;
 }
 
@@ -688,30 +681,21 @@ static void pci_restore_pcie_state(struct pci_dev *dev)
 
 static int pci_save_pcix_state(struct pci_dev *dev)
 {
-        int pos, i = 0;
+        int pos;
         struct pci_cap_saved_state *save_state;
-        u16 *cap;
-        int found = 0;
 
         pos = pci_find_capability(dev, PCI_CAP_ID_PCIX);
         if (pos <= 0)
                 return 0;
 
         save_state = pci_find_saved_cap(dev, PCI_CAP_ID_PCIX);
-        if (!save_state)
-                save_state = kzalloc(sizeof(*save_state) + sizeof(u16), GFP_KERNEL);
-        else
-                found = 1;
         if (!save_state) {
-                dev_err(&dev->dev, "out of memory in pci_save_pcie_state\n");
+                dev_err(&dev->dev, "buffer not found in %s\n", __FUNCTION__);
                 return -ENOMEM;
         }
-        cap = (u16 *)&save_state->data[0];
 
-        pci_read_config_word(dev, pos + PCI_X_CMD, &cap[i++]);
-        save_state->cap_nr = PCI_CAP_ID_PCIX;
-        if (!found)
-                pci_add_saved_cap(dev, save_state);
+        pci_read_config_word(dev, pos + PCI_X_CMD, (u16 *)save_state->data);
+
         return 0;
 }
 
@@ -1301,6 +1285,51 @@ void pci_pm_init(struct pci_dev *dev)
 }
 
 /**
+ * pci_add_save_buffer - allocate buffer for saving given capability registers
+ * @dev: the PCI device
+ * @cap: the capability to allocate the buffer for
+ * @size: requested size of the buffer
+ */
+static int pci_add_cap_save_buffer(
+        struct pci_dev *dev, char cap, unsigned int size)
+{
+        int pos;
+        struct pci_cap_saved_state *save_state;
+
+        pos = pci_find_capability(dev, cap);
+        if (pos <= 0)
+                return 0;
+
+        save_state = kzalloc(sizeof(*save_state) + size, GFP_KERNEL);
+        if (!save_state)
+                return -ENOMEM;
+
+        save_state->cap_nr = cap;
+        pci_add_saved_cap(dev, save_state);
+
+        return 0;
+}
+
+/**
+ * pci_allocate_cap_save_buffers - allocate buffers for saving capabilities
+ * @dev: the PCI device
+ */
+void pci_allocate_cap_save_buffers(struct pci_dev *dev)
+{
+        int error;
+
+        error = pci_add_cap_save_buffer(dev, PCI_CAP_ID_EXP, 4 * sizeof(u16));
+        if (error)
+                dev_err(&dev->dev,
+                        "unable to preallocate PCI Express save buffer\n");
+
+        error = pci_add_cap_save_buffer(dev, PCI_CAP_ID_PCIX, sizeof(u16));
+        if (error)
+                dev_err(&dev->dev,
+                        "unable to preallocate PCI-X save buffer\n");
+}
+
+/**
  * pci_enable_ari - enable ARI forwarding if hardware support it
  * @dev: the PCI device
  */