gpu: nvgpu: Fix race condition during poweron

When two or more apps ran simultaneously
First app context sets power_on flag & starts init
Other app context check the power_on flag
and try to use GPU without init completed
Which makes aother apps to assert

Added mutex to synchronize poweron access

Bug 200297265

Change-Id: Ie138f7f43bb0dd3304ed91ae3649a6a4947bee91
Signed-off-by: skadamati <skadamati@nvidia.com>
Reviewed-on: https://git-master/r/1511436
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>

2 files changed, 4 insertions, 0 deletions

diff --git a/drivers/gpu/nvgpu/common/linux/driver_common.c b/drivers/gpu/nvgpu/common/linux/driver_common.c
index c2bd9d78..b12917d6 100644
--- a/drivers/gpu/nvgpu/common/linux/driver_common.c
+++ b/drivers/gpu/nvgpu/common/linux/driver_common.c
@@ -50,6 +50,7 @@ static void nvgpu_init_vars(struct gk20a *g)
         nvgpu_mutex_init(&platform->railgate_lock);
         nvgpu_mutex_init(&g->dbg_sessions_lock);
         nvgpu_mutex_init(&g->client_lock);
+        nvgpu_mutex_init(&g->poweron_lock);
         nvgpu_mutex_init(&g->poweroff_lock);
 
         g->regs_saved = g->regs;
diff --git a/drivers/gpu/nvgpu/common/linux/module.c b/drivers/gpu/nvgpu/common/linux/module.c
index b107a721..0b5dfec8 100644
--- a/drivers/gpu/nvgpu/common/linux/module.c
+++ b/drivers/gpu/nvgpu/common/linux/module.c
@@ -88,15 +88,18 @@ int gk20a_busy(struct gk20a *g)
                         goto fail;
                 }
         } else {
+                nvgpu_mutex_acquire(&g->poweron_lock);
                 if (!g->power_on) {
                         ret = gk20a_gpu_is_virtual(dev) ?
                                 vgpu_pm_finalize_poweron(dev)
                                 : gk20a_pm_finalize_poweron(dev);
                         if (ret) {
                                 atomic_dec(&g->usage_count);
+                                nvgpu_mutex_release(&g->poweron_lock);
                                 goto fail;
                         }
                 }
+                nvgpu_mutex_release(&g->poweron_lock);
         }
 
 fail: