From e16dad6bfe1437aaee565f875a6713ca7ce81bdf Mon Sep 17 00:00:00 2001 From: Jake Oshins Date: Tue, 5 Apr 2016 10:22:50 -0700 Subject: [PATCH] drivers:hv: Lock access to hyperv_mmio resource tree In existing code, this tree of resources is created in single-threaded code and never modified after it is created, and thus needs no locking. This patch introduces a semaphore for tree access, as other patches in this series introduce run-time modifications of this resource tree which can happen on multiple threads. Signed-off-by: Jake Oshins Signed-off-by: K. Y. Srinivasan Signed-off-by: Greg Kroah-Hartman --- drivers/hv/vmbus_drv.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-) diff --git a/drivers/hv/vmbus_drv.c b/drivers/hv/vmbus_drv.c index 64713ff47e36..799518b3cdc5 100644 --- a/drivers/hv/vmbus_drv.c +++ b/drivers/hv/vmbus_drv.c @@ -102,6 +102,7 @@ static struct notifier_block hyperv_panic_block = { }; struct resource *hyperv_mmio; +DEFINE_SEMAPHORE(hyperv_mmio_lock); static int vmbus_exists(void) { @@ -1132,7 +1133,10 @@ int vmbus_allocate_mmio(struct resource **new, struct hv_device *device_obj, resource_size_t range_min, range_max, start, local_min, local_max; const char *dev_n = dev_name(&device_obj->device); u32 fb_end = screen_info.lfb_base + (screen_info.lfb_size << 1); - int i; + int i, retval; + + retval = -ENXIO; + down(&hyperv_mmio_lock); for (iter = hyperv_mmio; iter; iter = iter->sibling) { if ((iter->start >= max) || (iter->end <= min)) @@ -1169,13 +1173,17 @@ int vmbus_allocate_mmio(struct resource **new, struct hv_device *device_obj, for (; start + size - 1 <= local_max; start += align) { *new = request_mem_region_exclusive(start, size, dev_n); - if (*new) - return 0; + if (*new) { + retval = 0; + goto exit; + } } } } - return -ENXIO; +exit: + up(&hyperv_mmio_lock); + return retval; } EXPORT_SYMBOL_GPL(vmbus_allocate_mmio); -- 2.20.1