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 <ja...@microsoft.com>
---
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 64713ff..799518b 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);
--
1.9.1
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