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| author | Joerg Roedel <joerg.roedel@amd.com> | 2008-07-11 17:14:27 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2008-07-11 18:01:13 +0200 |
| commit | 136f78a19cf94d469f31a4009c7c0ac2301fbbf0 (patch) | |
| tree | 92055e77da5bb4874be1ff3936a16ead059d6701 /arch/x86/kernel/amd_iommu.c | |
| parent | 9a836de0c9944c42d006ec241712c72e74737c73 (diff) | |
| download | lwn-136f78a19cf94d469f31a4009c7c0ac2301fbbf0.tar.gz lwn-136f78a19cf94d469f31a4009c7c0ac2301fbbf0.zip | |
x86, AMD IOMMU: add an emergency exit to the completion wait loop
To make the loop waiting for the completion wait command not wait forever this
patch adds a limit of cycles that loop.
Signed-off-by: Joerg Roedel <joerg.roedel@amd.com>
Cc: iommu@lists.linux-foundation.org
Cc: bhavna.sarathy@amd.com
Cc: robert.richter@amd.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86/kernel/amd_iommu.c')
| -rw-r--r-- | arch/x86/kernel/amd_iommu.c | 10 |
1 files changed, 9 insertions, 1 deletions
diff --git a/arch/x86/kernel/amd_iommu.c b/arch/x86/kernel/amd_iommu.c index 9098f047c1a9..7fa2d5d57dd8 100644 --- a/arch/x86/kernel/amd_iommu.c +++ b/arch/x86/kernel/amd_iommu.c @@ -32,6 +32,8 @@ #define to_pages(addr, size) \ (round_up(((addr) & ~PAGE_MASK) + (size), PAGE_SIZE) >> PAGE_SHIFT) +#define EXIT_LOOP_COUNT 10000000 + static DEFINE_RWLOCK(amd_iommu_devtable_lock); /* @@ -106,6 +108,7 @@ static int iommu_completion_wait(struct amd_iommu *iommu) struct command cmd; volatile u64 ready = 0; unsigned long ready_phys = virt_to_phys(&ready); + unsigned long i = 0; memset(&cmd, 0, sizeof(cmd)); cmd.data[0] = LOW_U32(ready_phys) | CMD_COMPL_WAIT_STORE_MASK; @@ -120,8 +123,13 @@ static int iommu_completion_wait(struct amd_iommu *iommu) if (ret) return ret; - while (!ready) + while (!ready && (i < EXIT_LOOP_COUNT)) { + ++i; cpu_relax(); + } + + if (unlikely((i == EXIT_LOOP_COUNT) && printk_ratelimit())) + printk(KERN_WARNING "AMD IOMMU: Completion wait loop failed\n"); return 0; } |