Am 31.03.21 um 14:25 schrieb Rodrigo Siqueira:
DC invokes DC_FPU_START/END in multiple parts of the code; this can
create a situation where we invoke this FPU operation in a nested way.
For avoiding this situation, this commit adds a mechanism where
dc_fpu_begin/end manages the access to kernel_fpu_begin/end.
In general please name this "recursion" control instead of "ref count".
Let's call the child by it's name :)
Signed-off-by: Rodrigo Siqueira <Rodrigo.Siqueira@xxxxxxx>
Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira@xxxxxxx>
---
.../amd/display/amdgpu_dm/amdgpu_dm_trace.h | 13 ++++---
.../gpu/drm/amd/display/amdgpu_dm/dc_fpu.c | 34 ++++++++++++++++---
drivers/gpu/drm/amd/display/dc/dc_trace.h | 4 +--
3 files changed, 40 insertions(+), 11 deletions(-)
diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_trace.h b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_trace.h
index 230bb12c405e..cd4f0d3f37fb 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_trace.h
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm_trace.h
@@ -638,23 +638,26 @@ TRACE_EVENT(amdgpu_refresh_rate_track,
);
TRACE_EVENT(dcn_fpu,
- TP_PROTO(bool begin, const char *function, const int line),
- TP_ARGS(begin, function, line),
+ TP_PROTO(bool begin, const char *function, const int line, const int ref_count),
+ TP_ARGS(begin, function, line, ref_count),
TP_STRUCT__entry(
__field(bool, begin)
__field(const char *, function)
__field(int, line)
+ __field(int, ref_count)
),
TP_fast_assign(
__entry->begin = begin;
__entry->function = function;
__entry->line = line;
+ __entry->ref_count = ref_count;
),
- TP_printk("%s()+%d: %s",
+ TP_printk("%s: ref_count: %d: %s()+%d:",
+ __entry->begin ? "begin" : "end",
+ __entry->ref_count,
__entry->function,
- __entry->line,
- __entry->begin ? "begin" : "end"
+ __entry->line
)
);
diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/dc_fpu.c b/drivers/gpu/drm/amd/display/amdgpu_dm/dc_fpu.c
index ff34007509de..5dcefe193523 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/dc_fpu.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/dc_fpu.c
@@ -28,6 +28,19 @@
#include <asm/fpu/api.h>
+/**
+ * DOC: Overview
+ *
+ * DC core uses FPU operations in multiple parts of the code, which requires a
+ * more specialized way to manage these areas' entrance. To fulfill this
+ * requirement, we created some wrapper functions that encapsulate
+ * kernel_fpu_begin/end to better fit our need in the display component. In
+ * summary, in this file, you can find functions related to FPU operation
+ * management.
+ */
+
+static DEFINE_PER_CPU(atomic_t, fpu_ref);
+
/**
* dc_fpu_begin - Enables FPU protection
* @function_name: A string containing the function name for debug purposes
@@ -40,8 +53,14 @@
*/
void dc_fpu_begin(const char *function_name, const int line)
{
- TRACE_DCN_FPU(true, function_name, line);
- kernel_fpu_begin();
+ int ret;
+ atomic_t *local_fpu_ref = this_cpu_ptr(&fpu_ref);
+
+ ret = atomic_inc_return(local_fpu_ref);
You need to disable preemption for this or otherwise it can be that you
schedule to another process.
Regards,
Christian.
+ TRACE_DCN_FPU(true, function_name, line, ret);
+
+ if (ret == 1)
+ kernel_fpu_begin();
}
/**
@@ -56,6 +75,13 @@ void dc_fpu_begin(const char *function_name, const int line)
*/
void dc_fpu_end(const char *function_name, const int line)
{
- TRACE_DCN_FPU(false, function_name, line);
- kernel_fpu_end();
+
+ int ret;
+ atomic_t *local_fpu_ref = this_cpu_ptr(&fpu_ref);
+
+ ret = atomic_dec_return(local_fpu_ref);
+ TRACE_DCN_FPU(false, function_name, line, ret);
+
+ if (!ret)
+ kernel_fpu_end();
}
diff --git a/drivers/gpu/drm/amd/display/dc/dc_trace.h b/drivers/gpu/drm/amd/display/dc/dc_trace.h
index d598ba697e45..c711797e5c9e 100644
--- a/drivers/gpu/drm/amd/display/dc/dc_trace.h
+++ b/drivers/gpu/drm/amd/display/dc/dc_trace.h
@@ -38,5 +38,5 @@
#define TRACE_DCN_CLOCK_STATE(dcn_clocks) \
trace_amdgpu_dm_dc_clocks_state(dcn_clocks)
-#define TRACE_DCN_FPU(begin, function, line) \
- trace_dcn_fpu(begin, function, line)
+#define TRACE_DCN_FPU(begin, function, line, ref_count) \
+ trace_dcn_fpu(begin, function, line, ref_count)
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