Merge pull request #9186 from tkem/fix/ticker-read-us-race-cond

0xc0170 · web-flow · commit b4f1c2576789 · 2019-01-02T09:19:02.000Z
Fix ticker_read_us() race condition.
diff --git a/hal/mbed_ticker_api.c b/hal/mbed_ticker_api.c
@@ -416,13 +416,16 @@ timestamp_t ticker_read(const ticker_data_t *const ticker)
 
 us_timestamp_t ticker_read_us(const ticker_data_t *const ticker)
 {
+    us_timestamp_t ret;
+
     initialize(ticker);
 
     core_util_critical_section_enter();
     update_present_time(ticker);
+    ret = ticker->queue->present_time;
     core_util_critical_section_exit();
 
-    return ticker->queue->present_time;
+    return ret;
 }
 
 int ticker_get_next_timestamp(const ticker_data_t *const data, timestamp_t *timestamp)

Original file line number	Diff line number	Diff line change
`@@ -416,13 +416,16 @@ timestamp_t ticker_read(const ticker_data_t *const ticker)`
`416`	`416`
`417`	`417`	`us_timestamp_t ticker_read_us(const ticker_data_t *const ticker)`
`418`	`418`	`{`
	`419`	`+ us_timestamp_t ret;`
	`420`	`+`
`419`	`421`	`initialize(ticker);`
`420`	`422`
`421`	`423`	`core_util_critical_section_enter();`
`422`	`424`	`update_present_time(ticker);`
	`425`	`+ ret = ticker->queue->present_time;`
`423`	`426`	`core_util_critical_section_exit();`
`424`	`427`
`425`		`- return ticker->queue->present_time;`
	`428`	`+ return ret;`
`426`	`429`	`}`
`427`	`430`
`428`	`431`	`int ticker_get_next_timestamp(const ticker_data_t const data, timestamp_t timestamp)`