diff options
Diffstat (limited to 'drivers/iommu/dmar.c')
| -rw-r--r-- | drivers/iommu/dmar.c | 19 |
1 files changed, 16 insertions, 3 deletions
diff --git a/drivers/iommu/dmar.c b/drivers/iommu/dmar.c index 4ae6df27ad5d..c9aca8841fa0 100644 --- a/drivers/iommu/dmar.c +++ b/drivers/iommu/dmar.c @@ -43,10 +43,19 @@ #include "irq_remapping.h" -/* No locks are needed as DMA remapping hardware unit - * list is constructed at boot time and hotplug of - * these units are not supported by the architecture. +/* + * Assumptions: + * 1) The hotplug framework guarentees that DMAR unit will be hot-added + * before IO devices managed by that unit. + * 2) The hotplug framework guarantees that DMAR unit will be hot-removed + * after IO devices managed by that unit. + * 3) Hotplug events are rare. + * + * Locking rules for DMA and interrupt remapping related global data structures: + * 1) Use dmar_global_lock in process context + * 2) Use RCU in interrupt context */ +DECLARE_RWSEM(dmar_global_lock); LIST_HEAD(dmar_drhd_units); struct acpi_table_header * __initdata dmar_tbl; @@ -565,6 +574,7 @@ int __init detect_intel_iommu(void) { int ret; + down_write(&dmar_global_lock); ret = dmar_table_detect(); if (ret) ret = check_zero_address(); @@ -582,6 +592,7 @@ int __init detect_intel_iommu(void) } early_acpi_os_unmap_memory((void __iomem *)dmar_tbl, dmar_tbl_size); dmar_tbl = NULL; + up_write(&dmar_global_lock); return ret ? 1 : -ENODEV; } @@ -1394,10 +1405,12 @@ static int __init dmar_free_unused_resources(void) if (irq_remapping_enabled || intel_iommu_enabled) return 0; + down_write(&dmar_global_lock); list_for_each_entry_safe(dmaru, dmaru_n, &dmar_drhd_units, list) { list_del(&dmaru->list); dmar_free_drhd(dmaru); } + up_write(&dmar_global_lock); return 0; } |