[Mesa-dev] [PATCH] panfrost: Jobs must be per context, not per screen

Boris Brezillon boris.brezillon at collabora.com
Thu Aug 29 13:05:10 UTC 2019


On Thu, 29 Aug 2019 14:51:52 +0200
Rohan Garg <rohan.garg at collabora.com> wrote:

> Jobs _must_ only be shared across the same context, having
> the last_job tracked in a screen causes use-after-free issues
> and memory corruptions.

You should probably also mention that transient-pool and bo-cache
related fields should be protected by a mutex as they are shared by all
contexts. Or even better, split that patch in 2:

1/ move last_job, last_fragment_pushed to panfrost_context
2/ protect transient/bo-cache manipulation with mutexes

> 
> Signed-off-by: Rohan Garg <rohan.garg at collabora.com>
> ---
>  src/gallium/drivers/panfrost/pan_allocate.c |  2 ++
>  src/gallium/drivers/panfrost/pan_bo_cache.c | 16 +++++++++++-----
>  src/gallium/drivers/panfrost/pan_context.c  | 10 +++++-----
>  src/gallium/drivers/panfrost/pan_context.h  |  6 ++++++
>  src/gallium/drivers/panfrost/pan_drm.c      |  6 +++---
>  src/gallium/drivers/panfrost/pan_job.c      |  2 ++
>  src/gallium/drivers/panfrost/pan_screen.c   |  5 ++---
>  src/gallium/drivers/panfrost/pan_screen.h   | 10 ++++------
>  8 files changed, 35 insertions(+), 22 deletions(-)
> 
> diff --git a/src/gallium/drivers/panfrost/pan_allocate.c b/src/gallium/drivers/panfrost/pan_allocate.c
> index f549c864c70..fb8b18fe718 100644
> --- a/src/gallium/drivers/panfrost/pan_allocate.c
> +++ b/src/gallium/drivers/panfrost/pan_allocate.c
> @@ -74,6 +74,7 @@ panfrost_allocate_transient(struct panfrost_context *ctx, size_t sz)
>          unsigned offset = 0;
>          bool update_offset = false;
>  
> +        pthread_mutex_lock(&screen->transient_lock);
>          bool has_current = batch->transient_indices.size;
>          bool fits_in_current = (batch->transient_offset + sz) < TRANSIENT_SLAB_SIZE;
>  
> @@ -131,6 +132,7 @@ panfrost_allocate_transient(struct panfrost_context *ctx, size_t sz)
>  
>          if (update_offset)
>                  batch->transient_offset = offset + sz;
> +        pthread_mutex_unlock(&screen->transient_lock);
>  
>          return ret;
>  
> diff --git a/src/gallium/drivers/panfrost/pan_bo_cache.c b/src/gallium/drivers/panfrost/pan_bo_cache.c
> index 9dd6b694b72..f2f49437a89 100644
> --- a/src/gallium/drivers/panfrost/pan_bo_cache.c
> +++ b/src/gallium/drivers/panfrost/pan_bo_cache.c
> @@ -24,6 +24,7 @@
>   *   Alyssa Rosenzweig <alyssa.rosenzweig at collabora.com>
>   */
>  #include <xf86drm.h>
> +#include <pthread.h>
>  #include "drm-uapi/panfrost_drm.h"
>  
>  #include "pan_screen.h"
> @@ -84,7 +85,9 @@ panfrost_bo_cache_fetch(
>                  struct panfrost_screen *screen,
>                  size_t size, uint32_t flags)
>  {
> +        pthread_mutex_lock(&screen->bo_cache_lock);
>          struct list_head *bucket = pan_bucket(screen, size);
> +        struct panfrost_bo *bo = NULL;
>  
>          /* Iterate the bucket looking for something suitable */
>          list_for_each_entry_safe(struct panfrost_bo, entry, bucket, link) {
> @@ -106,12 +109,13 @@ panfrost_bo_cache_fetch(
>                                  continue;
>                          }
>                          /* Let's go! */
> -                        return entry;
> +                        bo = entry;
> +                        break;
>                  }
>          }
> +        pthread_mutex_unlock(&screen->bo_cache_lock);
>  
> -        /* We didn't find anything */
> -        return NULL;
> +        return bo;
>  }
>  
>  /* Tries to add a BO to the cache. Returns if it was
> @@ -122,6 +126,7 @@ panfrost_bo_cache_put(
>                  struct panfrost_screen *screen,
>                  struct panfrost_bo *bo)
>  {
> +        pthread_mutex_lock(&screen->bo_cache_lock);
>          struct list_head *bucket = pan_bucket(screen, bo->size);
>          struct drm_panfrost_madvise madv;
>  
> @@ -133,6 +138,7 @@ panfrost_bo_cache_put(
>  
>          /* Add us to the bucket */
>          list_addtail(&bo->link, bucket);
> +        pthread_mutex_unlock(&screen->bo_cache_lock);
>  
>          return true;
>  }
> @@ -147,6 +153,7 @@ void
>  panfrost_bo_cache_evict_all(
>                  struct panfrost_screen *screen)
>  {
> +        pthread_mutex_lock(&screen->bo_cache_lock);
>          for (unsigned i = 0; i < ARRAY_SIZE(screen->bo_cache); ++i) {
>                  struct list_head *bucket = &screen->bo_cache[i];
>  
> @@ -155,7 +162,6 @@ panfrost_bo_cache_evict_all(
>                          panfrost_drm_release_bo(screen, entry, false);
>                  }
>          }
> -
> -        return;
> +        pthread_mutex_unlock(&screen->bo_cache_lock);
>  }
>  
> diff --git a/src/gallium/drivers/panfrost/pan_context.c b/src/gallium/drivers/panfrost/pan_context.c
> index fa9c92af9f6..94ee9b5bdb2 100644
> --- a/src/gallium/drivers/panfrost/pan_context.c
> +++ b/src/gallium/drivers/panfrost/pan_context.c
> @@ -1329,9 +1329,6 @@ panfrost_submit_frame(struct panfrost_context *ctx, bool flush_immediate,
>                        struct pipe_fence_handle **fence,
>                        struct panfrost_job *job)
>  {
> -        struct pipe_context *gallium = (struct pipe_context *) ctx;
> -        struct panfrost_screen *screen = pan_screen(gallium->screen);
> -
>          panfrost_job_submit(ctx, job);
>  
>          /* If visual, we can stall a frame */
> @@ -1339,8 +1336,8 @@ panfrost_submit_frame(struct panfrost_context *ctx, bool flush_immediate,
>          if (!flush_immediate)
>                  panfrost_drm_force_flush_fragment(ctx, fence);
>  
> -        screen->last_fragment_flushed = false;
> -        screen->last_job = job;
> +        ctx->last_fragment_flushed = false;
> +        ctx->last_job = job;
>  
>          /* If readback, flush now (hurts the pipelined performance) */
>          if (flush_immediate)
> @@ -2856,6 +2853,9 @@ panfrost_create_context(struct pipe_screen *screen, void *priv, unsigned flags)
>          assert(ctx->blitter);
>          assert(ctx->blitter_wallpaper);
>  
> +        ctx->last_fragment_flushed = true;
> +        ctx->last_job = NULL;
> +
>          /* Prepare for render! */
>  
>          panfrost_job_init(ctx);
> diff --git a/src/gallium/drivers/panfrost/pan_context.h b/src/gallium/drivers/panfrost/pan_context.h
> index 4c1580b3393..9f96e983a86 100644
> --- a/src/gallium/drivers/panfrost/pan_context.h
> +++ b/src/gallium/drivers/panfrost/pan_context.h
> @@ -203,6 +203,12 @@ struct panfrost_context {
>          bool is_t6xx;
>  
>          uint32_t out_sync;
> +
> +        /* While we're busy building up the job for frame N, the GPU is
> +         * still busy executing frame N-1. So hold a reference to
> +         * yesterjob */
> +        int last_fragment_flushed;
> +        struct panfrost_job *last_job;
>  };
>  
>  /* Corresponds to the CSO */
> diff --git a/src/gallium/drivers/panfrost/pan_drm.c b/src/gallium/drivers/panfrost/pan_drm.c
> index c3693bff56a..f89bc1d26eb 100644
> --- a/src/gallium/drivers/panfrost/pan_drm.c
> +++ b/src/gallium/drivers/panfrost/pan_drm.c
> @@ -349,12 +349,12 @@ panfrost_drm_force_flush_fragment(struct panfrost_context *ctx,
>          struct pipe_context *gallium = (struct pipe_context *) ctx;
>          struct panfrost_screen *screen = pan_screen(gallium->screen);
>  
> -        if (!screen->last_fragment_flushed) {
> +        if (!ctx->last_fragment_flushed) {
>                  drmSyncobjWait(screen->fd, &ctx->out_sync, 1, INT64_MAX, 0, NULL);
> -                screen->last_fragment_flushed = true;
> +                ctx->last_fragment_flushed = true;
>  
>                  /* The job finished up, so we're safe to clean it up now */
> -                panfrost_free_job(ctx, screen->last_job);
> +                panfrost_free_job(ctx, ctx->last_job);
>          }
>  
>          if (fence) {
> diff --git a/src/gallium/drivers/panfrost/pan_job.c b/src/gallium/drivers/panfrost/pan_job.c
> index 4d8ec2eadc9..72afcdbf358 100644
> --- a/src/gallium/drivers/panfrost/pan_job.c
> +++ b/src/gallium/drivers/panfrost/pan_job.c
> @@ -67,10 +67,12 @@ panfrost_free_job(struct panfrost_context *ctx, struct panfrost_job *job)
>          /* Free up the transient BOs we're sitting on */
>          struct panfrost_screen *screen = pan_screen(ctx->base.screen);
>  
> +        pthread_mutex_lock(&screen->transiant_lock);
>          util_dynarray_foreach(&job->transient_indices, unsigned, index) {
>                  /* Mark it free */
>                  BITSET_SET(screen->free_transient, *index);
>          }
> +        pthread_mutex_unlock(&screen->transiant_lock);
>  
>          /* Unreference the polygon list */
>          panfrost_bo_unreference(ctx->base.screen, job->polygon_list);
> diff --git a/src/gallium/drivers/panfrost/pan_screen.c b/src/gallium/drivers/panfrost/pan_screen.c
> index 36c91a1572e..07f60ffee52 100644
> --- a/src/gallium/drivers/panfrost/pan_screen.c
> +++ b/src/gallium/drivers/panfrost/pan_screen.c
> @@ -639,8 +639,10 @@ panfrost_create_screen(int fd, struct renderonly *ro)
>                  return NULL;
>          }
>  
> +	pthread_mutex_init(&screen->transiant_lock, NULL);
>          util_dynarray_init(&screen->transient_bo, screen);
>  
> +	pthread_mutex_init(&screen->bo_cache_lock, NULL);
>          for (unsigned i = 0; i < ARRAY_SIZE(screen->bo_cache); ++i)
>                  list_inithead(&screen->bo_cache[i]);
>  
> @@ -665,9 +667,6 @@ panfrost_create_screen(int fd, struct renderonly *ro)
>          screen->base.fence_finish = panfrost_fence_finish;
>          screen->base.set_damage_region = panfrost_resource_set_damage_region;
>  
> -        screen->last_fragment_flushed = true;
> -        screen->last_job = NULL;
> -
>          panfrost_resource_screen_init(screen);
>  
>          return &screen->base;
> diff --git a/src/gallium/drivers/panfrost/pan_screen.h b/src/gallium/drivers/panfrost/pan_screen.h
> index 35fb8de2628..f83cd7562ab 100644
> --- a/src/gallium/drivers/panfrost/pan_screen.h
> +++ b/src/gallium/drivers/panfrost/pan_screen.h
> @@ -104,6 +104,8 @@ struct panfrost_screen {
>  
>          struct renderonly *ro;
>  
> +        pthread_mutex_t transient_lock;
> +
>          /* Transient memory management is based on borrowing fixed-size slabs
>           * off the screen (loaning them out to the batch). Dynamic array
>           * container of panfrost_bo */
> @@ -113,17 +115,13 @@ struct panfrost_screen {
>          /* Set of free transient BOs */
>          BITSET_DECLARE(free_transient, MAX_TRANSIENT_SLABS);
>  
> +        pthread_mutex_t bo_cache_lock;
> +
>          /* The BO cache is a set of buckets with power-of-two sizes ranging
>           * from 2^12 (4096, the page size) to 2^(12 + MAX_BO_CACHE_BUCKETS).
>           * Each bucket is a linked list of free panfrost_bo objects. */
>  
>          struct list_head bo_cache[NR_BO_CACHE_BUCKETS];
> -
> -        /* While we're busy building up the job for frame N, the GPU is
> -         * still busy executing frame N-1. So hold a reference to
> -         * yesterjob */
> -        int last_fragment_flushed;
> -        struct panfrost_job *last_job;
>  };
>  
>  static inline struct panfrost_screen *



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