[pci] pci/mrst: Detect loops when reading fixed BAR cap.
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From: Ben Greear on 14 Jul 2010 13:10 The mrst logic introduced in 2.6.33-rc8 in commit a712ffbc199849364c46e9112b93b66de08e2c26 causes boot to hang on at least this platform: Intel E5405 CPU System Information Manufacturer: Supermicro Product Name: X7DBU The cause of the hang is that pci_cap points to itself as the next capability, putting the fixed_bar_cap into an endless loop. This patch detects the loop, prints a warning, and continues on with useful work. This strategy was suggested by Robert Hancock <hancockrwd(a)gmail.com> This should be a candidate for 2.6.34.y as well. Signed-off-by: Ben Greear <greearb(a)candelatech.com> --- :100644 100644 1cdc02c... 9535ba9... M arch/x86/pci/mrst.c arch/x86/pci/mrst.c | 11 +++++++++++ 1 files changed, 11 insertions(+), 0 deletions(-) diff --git a/arch/x86/pci/mrst.c b/arch/x86/pci/mrst.c index 1cdc02c..9535ba9 100644 --- a/arch/x86/pci/mrst.c +++ b/arch/x86/pci/mrst.c @@ -76,6 +76,17 @@ static int fixed_bar_cap(struct pci_bus *bus, unsigned int devfn) return pos; } + if ((pcie_cap >> 20) == 0) + break; + + if ((pcie_cap >> 20) <= pos) { + printk(KERN_WARNING "WARNING: mrst: detected loop" + " when searching for fixed BAR cap, previous" + " position: 0x%x new position: 0x%x" + " bus-number: %i devfn: %i\n", + pos, pcie_cap >> 20, bus->number, devfn); + break; + } pos = pcie_cap >> 20; } -- 1.6.2.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |