gpu: nvgpu: fix crash with uninitialized comptag allocator

If gk20a_comptaglines_alloc() is called with an uninitialized comptag allocator
we right now see a kernel panic like this

[  445.097931] [<ffffff8008fdd650>] __mutex_lock_slowpath+0xe0/0x188
[  445.104275] [<ffffff8008fdd748>] mutex_lock+0x50/0x68
[  445.109773] [<ffffff80012ef340>] gk20a_comptaglines_alloc+0x30/0x98 [nvgpu]
[  445.117169] [<ffffff80012e0fdc>] gk20a_alloc_or_get_comptags+0xe4/0x140 [nvgpu]
[  445.124910] [<ffffff80012ee1cc>] nvgpu_vm_map+0x414/0x7b8 [nvgpu]
[  445.131433] [<ffffff80012dd754>] nvgpu_vm_map_linux+0x114/0x1e8 [nvgpu]
[  445.138475] [<ffffff80012dd978>] nvgpu_vm_map_buffer+0x150/0x238 [nvgpu]
[  445.145605] [<ffffff80012d2834>] gk20a_as_dev_ioctl+0x30c/0xa78 [nvgpu]
[  445.152473] [<ffffff8008262154>] do_vfs_ioctl+0xc4/0x8f8

Fix this by checking explicitly that comptag allocator is initialized in
gk20a_comptaglines_alloc() and gk20a_comptaglines_free()

Bug 2171567

Change-Id: Iaac6d77e40a8aaa01f2bacbe0cb54ec447100075
Signed-off-by: Deepak Nibade <dnibade@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/1805170
GVS: Gerrit_Virtual_Submit
Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>
Reviewed-by: Seshendra Gadagottu <sgadagottu@nvidia.com>
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>

1 files changed, 8 insertions, 0 deletions

diff --git a/drivers/gpu/nvgpu/common/mm/comptags.c b/drivers/gpu/nvgpu/common/mm/comptags.c
index 334236ec..3bde3a53 100644
--- a/drivers/gpu/nvgpu/common/mm/comptags.c
+++ b/drivers/gpu/nvgpu/common/mm/comptags.c
@@ -32,6 +32,10 @@ int gk20a_comptaglines_alloc(struct gk20a_comptag_allocator *allocator,
         unsigned long addr;
         int err = 0;
 
+        if (allocator->size == 0UL) {
+                return -EINVAL;
+        }
+
         nvgpu_mutex_acquire(&allocator->lock);
         addr = bitmap_find_next_zero_area(allocator->bitmap, allocator->size,
                         0, len, 0);
@@ -53,6 +57,10 @@ void gk20a_comptaglines_free(struct gk20a_comptag_allocator *allocator,
         /* number zero is reserved; bitmap base is 1 */
         u32 addr = offset - 1U;
 
+        if (allocator->size == 0UL) {
+                return;
+        }
+
         WARN_ON(offset == 0U);
         WARN_ON(addr > allocator->size);
         WARN_ON(addr + len > allocator->size);