drm/amd/display: Use atomic types for ref_count

Current ref_count inc/dec is not guarded by locks which leads to
a raced condition where two threads try to access the variable
at the same time. In this case, both might act on the same cached
value and inc/dec from the same value, rather than inc/dec by 2.

Signed-off-by: Jerry Zuo <Jerry.Zuo@amd.com>
Reviewed-by: Harry Wentland <Harry.Wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

diff --git a/drivers/gpu/drm/amd/display/dc/core/dc.c b/drivers/gpu/drm/amd/display/dc/core/dc.c
index b69a726717d98778caa1ec5dfbfd72d53698b557..8efdd05841e103b467af7e27367bc43a4d59313c 100644 (file)
--- a/drivers/gpu/drm/amd/display/dc/core/dc.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc.c
@@ -454,7 +454,7 @@ static bool construct(struct core_dc *dc,
                goto val_ctx_fail;
        }
 
-       dc->current_context->ref_count++;
+       atomic_inc(&dc->current_context->ref_count);
 
        dc_ctx->cgs_device = init_params->cgs_device;
        dc_ctx->driver_context = init_params->driver;
@@ -704,7 +704,7 @@ struct validate_context *dc_get_validate_context(
        if (context == NULL)
                goto context_alloc_fail;
 
-       ++context->ref_count;
+       atomic_inc(&context->ref_count);
 
        if (!is_validation_required(core_dc, set, set_count)) {
                dc_resource_validate_ctx_copy_construct(core_dc->current_context, context);
@@ -748,7 +748,7 @@ bool dc_validate_resources(
        if (context == NULL)
                goto context_alloc_fail;
 
-       ++context->ref_count;
+       atomic_inc(&context->ref_count);
 
        result = core_dc->res_pool->funcs->validate_with_context(
                                core_dc, set, set_count, context, NULL);
@@ -782,7 +782,7 @@ bool dc_validate_guaranteed(
        if (context == NULL)
                goto context_alloc_fail;
 
-       ++context->ref_count;
+       atomic_inc(&context->ref_count);
 
        result = core_dc->res_pool->funcs->validate_guaranteed(
                                        core_dc, stream, context);
@@ -1090,7 +1090,7 @@ bool dc_commit_streams(
        if (context == NULL)
                goto context_alloc_fail;
 
-       ++context->ref_count;
+       atomic_inc(&context->ref_count);
 
        result = core_dc->res_pool->funcs->validate_with_context(
                        core_dc, set, stream_count, context, core_dc->current_context);
@@ -1203,16 +1203,16 @@ bool dc_commit_planes_to_stream(
 
 void dc_retain_validate_context(struct validate_context *context)
 {
-       ASSERT(context->ref_count > 0);
-       ++context->ref_count;
+       ASSERT(atomic_read(&context->ref_count) > 0);
+       atomic_inc(&context->ref_count);
 }
 
 void dc_release_validate_context(struct validate_context *context)
 {
-       ASSERT(context->ref_count > 0);
-       --context->ref_count;
+       ASSERT(atomic_read(&context->ref_count) > 0);
+       atomic_dec(&context->ref_count);
 
-       if (context->ref_count == 0) {
+       if (atomic_read(&context->ref_count) == 0) {
                dc_resource_validate_ctx_destruct(context);
                dm_free(context);
        }
@@ -1485,7 +1485,7 @@ void dc_update_planes_and_stream(struct dc *dc,
                if (context == NULL)
                                goto context_alloc_fail;
 
-               ++context->ref_count;
+               atomic_inc(&context->ref_count);
 
                dc_resource_validate_ctx_copy_construct(
                                core_dc->current_context, context);
@@ -1800,7 +1800,7 @@ void dc_set_power_state(
        enum dc_acpi_cm_power_state power_state)
 {
        struct core_dc *core_dc = DC_TO_CORE(dc);
-       int ref_count;
+       atomic_t ref_count;
 
        switch (power_state) {
        case DC_ACPI_CM_POWER_STATE_D0:

diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_resource.c b/drivers/gpu/drm/amd/display/dc/core/dc_resource.c
index 56a85c80131d8cf4d1cb65e6acca0e8d07d8f23f..1d69bd25e07b25b6c50b48015b08a1bea1fa33bc 100644 (file)
--- a/drivers/gpu/drm/amd/display/dc/core/dc_resource.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_resource.c
@@ -2238,7 +2238,7 @@ void dc_resource_validate_ctx_copy_construct(
                struct validate_context *dst_ctx)
 {
        int i, j;
-       int ref_count = dst_ctx->ref_count;
+       atomic_t ref_count = dst_ctx->ref_count;
 
        *dst_ctx = *src_ctx;
 

diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_sink.c b/drivers/gpu/drm/amd/display/dc/core/dc_sink.c
index a83f1243a9d1344a9d297228c8598a867b4b7814..7717350297a54fddef7de4285309b84c2dbe93af 100644 (file)
--- a/drivers/gpu/drm/amd/display/dc/core/dc_sink.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_sink.c
@@ -63,16 +63,16 @@ static bool construct(struct dc_sink *sink, const struct dc_sink_init_data *init
 
 void dc_sink_retain(struct dc_sink *sink)
 {
-       ASSERT(sink->ref_count > 0);
-       ++sink->ref_count;
+       ASSERT(atomic_read(&sink->ref_count) > 0);
+       atomic_inc(&sink->ref_count);
 }
 
 void dc_sink_release(struct dc_sink *sink)
 {
-       ASSERT(sink->ref_count > 0);
-       --sink->ref_count;
+       ASSERT(atomic_read(&sink->ref_count) > 0);
+       atomic_dec(&sink->ref_count);
 
-       if (sink->ref_count == 0) {
+       if (atomic_read(&sink->ref_count) == 0) {
                destruct(sink);
                dm_free(sink);
        }
@@ -88,7 +88,7 @@ struct dc_sink *dc_sink_create(const struct dc_sink_init_data *init_params)
        if (false == construct(sink, init_params))
                goto construct_fail;
 
-       ++sink->ref_count;
+       atomic_inc(&sink->ref_count);
 
        return sink;
 

diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_stream.c b/drivers/gpu/drm/amd/display/dc/core/dc_stream.c
index 2de37fed12a5839c9c2b3e845ea55d2306a6686f..47e407dab4a3dc3387355f992f962f3bb38d52ad 100644 (file)
--- a/drivers/gpu/drm/amd/display/dc/core/dc_stream.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_stream.c
@@ -96,19 +96,17 @@ static void destruct(struct dc_stream_state *stream)
 
 void dc_stream_retain(struct dc_stream_state *stream)
 {
-
-       ASSERT(stream->ref_count > 0);
-       stream->ref_count++;
+       ASSERT(atomic_read(&stream->ref_count) > 0);
+       atomic_inc(&stream->ref_count);
 }
 
 void dc_stream_release(struct dc_stream_state *stream)
 {
-
        if (stream != NULL) {
-               ASSERT(stream->ref_count > 0);
-               stream->ref_count--;
+               ASSERT(atomic_read(&stream->ref_count) > 0);
+               atomic_dec(&stream->ref_count);
 
-               if (stream->ref_count == 0) {
+               if (atomic_read(&stream->ref_count) == 0) {
                        destruct(stream);
                        dm_free(stream);
                }
@@ -131,7 +129,7 @@ struct dc_stream_state *dc_create_stream_for_sink(
        if (false == construct(stream, sink))
                        goto construct_fail;
 
-       stream->ref_count++;
+       atomic_inc(&stream->ref_count);
 
        return stream;
 

diff --git a/drivers/gpu/drm/amd/display/dc/core/dc_surface.c b/drivers/gpu/drm/amd/display/dc/core/dc_surface.c
index 3bcca2d1872b807985d30ed8aeda544322540106..da19c7fa5151eabecf5041762473a0bb38acff50 100644 (file)
--- a/drivers/gpu/drm/amd/display/dc/core/dc_surface.c
+++ b/drivers/gpu/drm/amd/display/dc/core/dc_surface.c
@@ -76,7 +76,7 @@ struct dc_plane_state *dc_create_plane_state(const struct dc *dc)
        if (false == construct(core_dc->ctx, plane_state))
                goto construct_fail;
 
-       ++plane_state->ref_count;
+       atomic_inc(&plane_state->ref_count);
 
        return plane_state;
 
@@ -122,16 +122,16 @@ const struct dc_plane_status *dc_plane_get_status(
 
 void dc_plane_state_retain(struct dc_plane_state *plane_state)
 {
-       ASSERT(plane_state->ref_count > 0);
-       ++plane_state->ref_count;
+       ASSERT(atomic_read(&plane_state->ref_count) > 0);
+       atomic_inc(&plane_state->ref_count);
 }
 
 void dc_plane_state_release(struct dc_plane_state *plane_state)
 {
-       ASSERT(plane_state->ref_count > 0);
-       --plane_state->ref_count;
+       ASSERT(atomic_read(&plane_state->ref_count) > 0);
+       atomic_dec(&plane_state->ref_count);
 
-       if (plane_state->ref_count == 0) {
+       if (atomic_read(&plane_state->ref_count) == 0) {
                destruct(plane_state);
                dm_free(plane_state);
        }
@@ -139,16 +139,16 @@ void dc_plane_state_release(struct dc_plane_state *plane_state)
 
 void dc_gamma_retain(struct dc_gamma *gamma)
 {
-       ASSERT(gamma->ref_count > 0);
-       ++gamma->ref_count;
+       ASSERT(atomic_read(&gamma->ref_count) > 0);
+       atomic_inc(&gamma->ref_count);
 }
 
 void dc_gamma_release(struct dc_gamma **gamma)
 {
-       ASSERT((*gamma)->ref_count > 0);
-       --(*gamma)->ref_count;
+       ASSERT(atomic_read(&(*gamma)->ref_count) > 0);
+       atomic_dec(&(*gamma)->ref_count);
 
-       if ((*gamma)->ref_count == 0)
+       if (atomic_read(&(*gamma)->ref_count) == 0)
                dm_free((*gamma));
 
        *gamma = NULL;
@@ -161,7 +161,7 @@ struct dc_gamma *dc_create_gamma()
        if (gamma == NULL)
                goto alloc_fail;
 
-       ++gamma->ref_count;
+       atomic_inc(&gamma->ref_count);
 
        return gamma;
 
@@ -171,16 +171,16 @@ alloc_fail:
 
 void dc_transfer_func_retain(struct dc_transfer_func *tf)
 {
-       ASSERT(tf->ref_count > 0);
-       ++tf->ref_count;
+       ASSERT(atomic_read(&tf->ref_count) > 0);
+       atomic_inc(&tf->ref_count);
 }
 
 void dc_transfer_func_release(struct dc_transfer_func *tf)
 {
-       ASSERT(tf->ref_count > 0);
-       --tf->ref_count;
+       ASSERT(atomic_read(&tf->ref_count) > 0);
+       atomic_dec(&tf->ref_count);
 
-       if (tf->ref_count == 0)
+       if (atomic_read(&tf->ref_count) == 0)
                dm_free(tf);
 }
 
@@ -191,7 +191,7 @@ struct dc_transfer_func *dc_create_transfer_func()
        if (tf == NULL)
                goto alloc_fail;
 
-       ++tf->ref_count;
+       atomic_inc(&tf->ref_count);
 
        return tf;
 

diff --git a/drivers/gpu/drm/amd/display/dc/dc.h b/drivers/gpu/drm/amd/display/dc/dc.h
index cac92bf91e4a7980302880424723a307e2037d57..4e60adb981e11d87aa0c2926aa43e4ab21764a44 100644 (file)
--- a/drivers/gpu/drm/amd/display/dc/dc.h
+++ b/drivers/gpu/drm/amd/display/dc/dc.h
@@ -295,7 +295,7 @@ struct dc_transfer_func {
        enum dc_transfer_func_type type;
        enum dc_transfer_func_predefined tf;
        struct dc_context *ctx;
-       int ref_count;
+       atomic_t ref_count;
 };
 
 /*
@@ -342,7 +342,7 @@ struct dc_plane_state {
 
        /* private to dc_surface.c */
        enum dc_irq_source irq_source;
-       int ref_count;
+       atomic_t ref_count;
 };
 
 struct dc_plane_info {
@@ -518,7 +518,7 @@ struct dc_stream_state {
        struct dc_stream_status status;
 
        /* from stream struct */
-       int ref_count;
+       atomic_t ref_count;
 };
 
 struct dc_stream_update {
@@ -902,7 +902,7 @@ struct dc_sink {
        struct dc_context *ctx;
 
        /* private to dc_sink.c */
-       int ref_count;
+       atomic_t ref_count;
 };
 
 void dc_sink_retain(struct dc_sink *sink);

diff --git a/drivers/gpu/drm/amd/display/dc/dc_hw_types.h b/drivers/gpu/drm/amd/display/dc/dc_hw_types.h
index 8d1504668ec72bd6f547c4a21efa923ef6686e02..94f83cd9ab32ce0dc933f5e9a31644ffd61360b1 100644 (file)
--- a/drivers/gpu/drm/amd/display/dc/dc_hw_types.h
+++ b/drivers/gpu/drm/amd/display/dc/dc_hw_types.h
@@ -433,7 +433,7 @@ struct dc_gamma {
        struct dc_context *ctx;
 
        /* private to dc_surface.c */
-       int ref_count;
+       atomic_t ref_count;
 };
 
 /* Used by both ipp amd opp functions*/

diff --git a/drivers/gpu/drm/amd/display/dc/inc/core_types.h b/drivers/gpu/drm/amd/display/dc/inc/core_types.h
index b3005629ab21801d150833fd4eb78c4a5212520c..5190901ea3797ff3e0717881dc6997c28eec708e 100644 (file)
--- a/drivers/gpu/drm/amd/display/dc/inc/core_types.h
+++ b/drivers/gpu/drm/amd/display/dc/inc/core_types.h
@@ -260,7 +260,7 @@ struct validate_context {
        struct dcn_bw_internal_vars dcn_bw_vars;
 #endif
 
-       int ref_count;
+       atomic_t ref_count;
 };
 
 #endif /* _CORE_TYPES_H_ */