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drm/i915: Fixup userptr mmu notifier registration error handling 

Avoid dereferencing the error pointer and also avoid returning NULL
from i915_mmu_notifier_find since the callers do not expect that.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Fixes: 7741b547b6 ("drm/i915: Preallocate our mmu notifier workequeu to unbreak cpu hotplug deadlock")
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Link: https://patchwork.freedesktop.org/patch/msgid/20171017150908.12840-1-tvrtko.ursulin@linux.intel.com
This commit is contained in:
Tvrtko Ursulin 2017-10-17 16:09:08 +01:00
parent 930a784d02
commit cb8d50dfb3
1 changed files with 6 additions and 4 deletions
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10
drivers/gpu/drm/i915/i915_gem_userptr.c
View File

@ -221,15 +221,17 @@ i915_mmu_notifier_find(struct i915_mm_struct *mm)
/* Protected by mm_lock */
mm->mn = fetch_and_zero(&mn);
}
} else {
/* someone else raced and successfully installed the mmu
* notifier, we can cancel our own errors */
} else if (mm->mn) {
/*
* Someone else raced and successfully installed the mmu
* notifier, we can cancel our own errors.
*/
err = 0;
}
mutex_unlock(&mm->i915->mm_lock);
up_write(&mm->mm->mmap_sem);
if (mn) {
if (mn && !IS_ERR(mn)) {
destroy_workqueue(mn->wq);
kfree(mn);
}