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Fix race condition in multi-threading initialization.

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Before, a first thread could enter VP8LDspInitSSE2, set
VP8LPredictorsAdd to an SSE2 version BEFORE another thread
would do the memcpy from VP8LPredictorsAdd to VP8LPredictorsAdd_C
thus leading to a C version actually being the SSE2 one (which
would then create an infinite recursion in the SSE2 predictors
at execution).

Change-Id: I224f4ceab31d38f77a1375a7e2636a6014080e3a
This commit is contained in:
Vincent Rabaud 2016-12-02 18:28:57 +01:00
parent 67879e6d48
commit 647045305a
1 changed files with 24 additions and 35 deletions
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59
src/dsp/lossless.c
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@ -581,44 +581,32 @@ extern void VP8LDspInitMSA(void);
static volatile VP8CPUInfo lossless_last_cpuinfo_used = static volatile VP8CPUInfo lossless_last_cpuinfo_used =
(VP8CPUInfo)&lossless_last_cpuinfo_used; (VP8CPUInfo)&lossless_last_cpuinfo_used;
#define COPY_PREDICTOR_ARRAY(IN, OUT) do { \
(OUT)[0] = IN##0; \
(OUT)[1] = IN##1; \
(OUT)[2] = IN##2; \
(OUT)[3] = IN##3; \
(OUT)[4] = IN##4; \
(OUT)[5] = IN##5; \
(OUT)[6] = IN##6; \
(OUT)[7] = IN##7; \
(OUT)[8] = IN##8; \
(OUT)[9] = IN##9; \
(OUT)[10] = IN##10; \
(OUT)[11] = IN##11; \
(OUT)[12] = IN##12; \
(OUT)[13] = IN##13; \
(OUT)[14] = IN##0; /* <- padding security sentinels*/ \
(OUT)[15] = IN##0; \
} while (0);
WEBP_TSAN_IGNORE_FUNCTION void VP8LDspInit(void) { WEBP_TSAN_IGNORE_FUNCTION void VP8LDspInit(void) {
if (lossless_last_cpuinfo_used == VP8GetCPUInfo) return; if (lossless_last_cpuinfo_used == VP8GetCPUInfo) return;
VP8LPredictors[0] = Predictor0; COPY_PREDICTOR_ARRAY(Predictor, VP8LPredictors)
VP8LPredictors[1] = Predictor1; COPY_PREDICTOR_ARRAY(Predictor, VP8LPredictors_C)
VP8LPredictors[2] = Predictor2; COPY_PREDICTOR_ARRAY(PredictorAdd, VP8LPredictorsAdd)
VP8LPredictors[3] = Predictor3; COPY_PREDICTOR_ARRAY(PredictorAdd, VP8LPredictorsAdd_C)
VP8LPredictors[4] = Predictor4;
VP8LPredictors[5] = Predictor5;
VP8LPredictors[6] = Predictor6;
VP8LPredictors[7] = Predictor7;
VP8LPredictors[8] = Predictor8;
VP8LPredictors[9] = Predictor9;
VP8LPredictors[10] = Predictor10;
VP8LPredictors[11] = Predictor11;
VP8LPredictors[12] = Predictor12;
VP8LPredictors[13] = Predictor13;
VP8LPredictors[14] = Predictor0; // <- padding security sentinels
VP8LPredictors[15] = Predictor0;
memcpy(VP8LPredictors_C, VP8LPredictors, sizeof(VP8LPredictors));
VP8LPredictorsAdd[0] = PredictorAdd0;
VP8LPredictorsAdd[1] = PredictorAdd1;
VP8LPredictorsAdd[2] = PredictorAdd2;
VP8LPredictorsAdd[3] = PredictorAdd3;
VP8LPredictorsAdd[4] = PredictorAdd4;
VP8LPredictorsAdd[5] = PredictorAdd5;
VP8LPredictorsAdd[6] = PredictorAdd6;
VP8LPredictorsAdd[7] = PredictorAdd7;
VP8LPredictorsAdd[8] = PredictorAdd8;
VP8LPredictorsAdd[9] = PredictorAdd9;
VP8LPredictorsAdd[10] = PredictorAdd10;
VP8LPredictorsAdd[11] = PredictorAdd11;
VP8LPredictorsAdd[12] = PredictorAdd12;
VP8LPredictorsAdd[13] = PredictorAdd13;
VP8LPredictorsAdd[14] = PredictorAdd0; // <- padding security sentinels
VP8LPredictorsAdd[15] = PredictorAdd0;
memcpy(VP8LPredictorsAdd_C, VP8LPredictorsAdd, sizeof(VP8LPredictorsAdd));
VP8LAddGreenToBlueAndRed = VP8LAddGreenToBlueAndRed_C; VP8LAddGreenToBlueAndRed = VP8LAddGreenToBlueAndRed_C;
@ -658,5 +646,6 @@ WEBP_TSAN_IGNORE_FUNCTION void VP8LDspInit(void) {
} }
lossless_last_cpuinfo_used = VP8GetCPUInfo; lossless_last_cpuinfo_used = VP8GetCPUInfo;
} }
#undef COPY_PREDICTOR_ARRAY
//------------------------------------------------------------------------------ //------------------------------------------------------------------------------