linux-kernel - [139/197] PCI: fix nested spinlock hang in aer

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Date:	Thu, 22 Apr 2010 12:09:50 -0700
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...nel.org
Cc:	stable-review@...nel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	Huang Ying <ying.huang@...el.com>,
	Andrew Patterson <andrew.patterson@...com>,
	Jesse Barnes <jbarnes@...tuousgeek.org>,
	maximilian attems <max@...o.at>
Subject: [139/197] PCI: fix nested spinlock hang in aer_inject

2.6.32-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Andrew Patterson <andrew.patterson@...com>

commit bd1f46deba615971a58193afd0202878cadf19a7 upstream.

The aer_inject module hangs in aer_inject() when checking the device's
error masks.  The hang is due to a recursive use of the aer_inject lock.
The aer_inject() routine grabs the lock while processing the error and then
calls pci_read_config_dword to read the masks. The pci_read_config_dword
routine is earlier overridden by pci_read_aer, which among other things,
grabs the aer_inject lock.

Fixed by moving the pci_read_config_dword calls to read the masks to before
the lock is taken.

Acked-by: Huang Ying <ying.huang@...el.com>
Signed-off-by: Andrew Patterson <andrew.patterson@...com>
Signed-off-by: Jesse Barnes <jbarnes@...tuousgeek.org>
Cc: maximilian attems <max@...o.at>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>

---
 drivers/pci/pcie/aer/aer_inject.c |   12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

--- a/drivers/pci/pcie/aer/aer_inject.c
+++ b/drivers/pci/pcie/aer/aer_inject.c
@@ -302,7 +302,7 @@ static int aer_inject(struct aer_error_i
 	unsigned long flags;
 	unsigned int devfn = PCI_DEVFN(einj->dev, einj->fn);
 	int pos_cap_err, rp_pos_cap_err;
-	u32 sever, mask;
+	u32 sever, cor_mask, uncor_mask;
 	int ret = 0;
 
 	dev = pci_get_bus_and_slot(einj->bus, devfn);
@@ -320,6 +320,9 @@ static int aer_inject(struct aer_error_i
 		goto out_put;
 	}
 	pci_read_config_dword(dev, pos_cap_err + PCI_ERR_UNCOR_SEVER, &sever);
+	pci_read_config_dword(dev, pos_cap_err + PCI_ERR_COR_MASK, &cor_mask);
+	pci_read_config_dword(dev, pos_cap_err + PCI_ERR_UNCOR_MASK,
+			      &uncor_mask);
 
 	rp_pos_cap_err = pci_find_ext_capability(rpdev, PCI_EXT_CAP_ID_ERR);
 	if (!rp_pos_cap_err) {
@@ -354,17 +357,14 @@ static int aer_inject(struct aer_error_i
 	err->header_log2 = einj->header_log2;
 	err->header_log3 = einj->header_log3;
 
-	pci_read_config_dword(dev, pos_cap_err + PCI_ERR_COR_MASK, &mask);
-	if (einj->cor_status && !(einj->cor_status & ~mask)) {
+	if (einj->cor_status && !(einj->cor_status & ~cor_mask)) {
 		ret = -EINVAL;
 		printk(KERN_WARNING "The correctable error(s) is masked "
 				"by device\n");
 		spin_unlock_irqrestore(&inject_lock, flags);
 		goto out_put;
 	}
-
-	pci_read_config_dword(dev, pos_cap_err + PCI_ERR_UNCOR_MASK, &mask);
-	if (einj->uncor_status && !(einj->uncor_status & ~mask)) {
+	if (einj->uncor_status && !(einj->uncor_status & ~uncor_mask)) {
 		ret = -EINVAL;
 		printk(KERN_WARNING "The uncorrectable error(s) is masked "
 				"by device\n");


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