[Intel-gfx] [PATCH] drm/i915: Nuke struct_mutex from context_setparam
Tvrtko Ursulin
tvrtko.ursulin at linux.intel.com
Tue Sep 11 13:34:03 UTC 2018
On 11/09/2018 14:22, Chris Wilson wrote:
> Userspace should be free to race against itself and shoot itself in
> the foot if it so desires to adjust a parameter at the same time as
> submitting a batch to that context. As such, the struct_mutex in context
> setparam is only being used to serialise userspace against itself and
> not for any protection of internal structs and so is superfluous.
>
> v2: Separate user_flags from internal flags to reduce chance of
> interference; and use locked bit ops for user updates.
Okay, email criss-cross!
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> ---
> drivers/gpu/drm/i915/i915_gem_context.c | 20 +++++--------
> drivers/gpu/drm/i915/i915_gem_context.h | 33 +++++++++++++---------
> drivers/gpu/drm/i915/i915_gem_execbuffer.c | 2 +-
> 3 files changed, 27 insertions(+), 28 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c
> index 747b8170a15a..f772593b99ab 100644
> --- a/drivers/gpu/drm/i915/i915_gem_context.c
> +++ b/drivers/gpu/drm/i915/i915_gem_context.c
> @@ -862,7 +862,7 @@ int i915_gem_context_getparam_ioctl(struct drm_device *dev, void *data,
> ret = -EINVAL;
> break;
> case I915_CONTEXT_PARAM_NO_ZEROMAP:
> - args->value = ctx->flags & CONTEXT_NO_ZEROMAP;
> + args->value = test_bit(UCONTEXT_NO_ZEROMAP, &ctx->user_flags);
> break;
> case I915_CONTEXT_PARAM_GTT_SIZE:
> if (ctx->ppgtt)
> @@ -896,27 +896,23 @@ int i915_gem_context_setparam_ioctl(struct drm_device *dev, void *data,
> struct drm_i915_file_private *file_priv = file->driver_priv;
> struct drm_i915_gem_context_param *args = data;
> struct i915_gem_context *ctx;
> - int ret;
> + int ret = 0;
>
> ctx = i915_gem_context_lookup(file_priv, args->ctx_id);
> if (!ctx)
> return -ENOENT;
>
> - ret = i915_mutex_lock_interruptible(dev);
> - if (ret)
> - goto out;
> -
> switch (args->param) {
> case I915_CONTEXT_PARAM_BAN_PERIOD:
> ret = -EINVAL;
> break;
> case I915_CONTEXT_PARAM_NO_ZEROMAP:
> - if (args->size) {
> + if (args->size)
> ret = -EINVAL;
> - } else {
> - ctx->flags &= ~CONTEXT_NO_ZEROMAP;
> - ctx->flags |= args->value ? CONTEXT_NO_ZEROMAP : 0;
> - }
> + else if (args->value)
> + set_bit(UCONTEXT_NO_ZEROMAP, &ctx->user_flags);
> + else
> + clear_bit(UCONTEXT_NO_ZEROMAP, &ctx->user_flags);
> break;
> case I915_CONTEXT_PARAM_NO_ERROR_CAPTURE:
> if (args->size)
> @@ -960,9 +956,7 @@ int i915_gem_context_setparam_ioctl(struct drm_device *dev, void *data,
> ret = -EINVAL;
> break;
> }
> - mutex_unlock(&dev->struct_mutex);
>
> -out:
> i915_gem_context_put(ctx);
> return ret;
> }
> diff --git a/drivers/gpu/drm/i915/i915_gem_context.h b/drivers/gpu/drm/i915/i915_gem_context.h
> index e09673ca731d..08165f6a0a84 100644
> --- a/drivers/gpu/drm/i915/i915_gem_context.h
> +++ b/drivers/gpu/drm/i915/i915_gem_context.h
> @@ -116,16 +116,21 @@ struct i915_gem_context {
> */
> struct rcu_head rcu;
>
> + /**
> + * @user_flags: small set of booleans controlled by the user
> + */
> + unsigned long user_flags;
> +#define UCONTEXT_NO_ZEROMAP 0
> +#define UCONTEXT_NO_ERROR_CAPTURE 1
> +#define UCONTEXT_BANNABLE 2
> +
> /**
> * @flags: small set of booleans
> */
> unsigned long flags;
> -#define CONTEXT_NO_ZEROMAP BIT(0)
> -#define CONTEXT_NO_ERROR_CAPTURE 1
> -#define CONTEXT_CLOSED 2
> -#define CONTEXT_BANNABLE 3
> -#define CONTEXT_BANNED 4
> -#define CONTEXT_FORCE_SINGLE_SUBMISSION 5
> +#define CONTEXT_BANNED 0
> +#define CONTEXT_CLOSED 1
> +#define CONTEXT_FORCE_SINGLE_SUBMISSION 2
>
> /**
> * @hw_id: - unique identifier for the context
> @@ -209,37 +214,37 @@ static inline bool i915_gem_context_is_closed(const struct i915_gem_context *ctx
> static inline void i915_gem_context_set_closed(struct i915_gem_context *ctx)
> {
> GEM_BUG_ON(i915_gem_context_is_closed(ctx));
> - __set_bit(CONTEXT_CLOSED, &ctx->flags);
> + set_bit(CONTEXT_CLOSED, &ctx->flags);
> }
>
> static inline bool i915_gem_context_no_error_capture(const struct i915_gem_context *ctx)
> {
> - return test_bit(CONTEXT_NO_ERROR_CAPTURE, &ctx->flags);
> + return test_bit(UCONTEXT_NO_ERROR_CAPTURE, &ctx->user_flags);
> }
>
> static inline void i915_gem_context_set_no_error_capture(struct i915_gem_context *ctx)
> {
> - __set_bit(CONTEXT_NO_ERROR_CAPTURE, &ctx->flags);
> + set_bit(UCONTEXT_NO_ERROR_CAPTURE, &ctx->user_flags);
> }
>
> static inline void i915_gem_context_clear_no_error_capture(struct i915_gem_context *ctx)
> {
> - __clear_bit(CONTEXT_NO_ERROR_CAPTURE, &ctx->flags);
> + clear_bit(UCONTEXT_NO_ERROR_CAPTURE, &ctx->user_flags);
> }
>
> static inline bool i915_gem_context_is_bannable(const struct i915_gem_context *ctx)
> {
> - return test_bit(CONTEXT_BANNABLE, &ctx->flags);
> + return test_bit(UCONTEXT_BANNABLE, &ctx->user_flags);
> }
>
> static inline void i915_gem_context_set_bannable(struct i915_gem_context *ctx)
> {
> - __set_bit(CONTEXT_BANNABLE, &ctx->flags);
> + set_bit(UCONTEXT_BANNABLE, &ctx->user_flags);
> }
>
> static inline void i915_gem_context_clear_bannable(struct i915_gem_context *ctx)
> {
> - __clear_bit(CONTEXT_BANNABLE, &ctx->flags);
> + clear_bit(UCONTEXT_BANNABLE, &ctx->user_flags);
> }
>
> static inline bool i915_gem_context_is_banned(const struct i915_gem_context *ctx)
> @@ -249,7 +254,7 @@ static inline bool i915_gem_context_is_banned(const struct i915_gem_context *ctx
>
> static inline void i915_gem_context_set_banned(struct i915_gem_context *ctx)
> {
> - __set_bit(CONTEXT_BANNED, &ctx->flags);
> + set_bit(CONTEXT_BANNED, &ctx->flags);
> }
>
> static inline bool i915_gem_context_force_single_submission(const struct i915_gem_context *ctx)
> diff --git a/drivers/gpu/drm/i915/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> index 22b4cb775576..aaa8a26aae86 100644
> --- a/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> +++ b/drivers/gpu/drm/i915/i915_gem_execbuffer.c
> @@ -743,7 +743,7 @@ static int eb_select_context(struct i915_execbuffer *eb)
> }
>
> eb->context_flags = 0;
> - if (ctx->flags & CONTEXT_NO_ZEROMAP)
> + if (test_bit(UCONTEXT_NO_ZEROMAP, &ctx->user_flags))
> eb->context_flags |= __EXEC_OBJECT_NEEDS_BIAS;
>
> return 0;
>
LGTM.
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
Regards,
Tvrtko
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