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HAL_ChibiOS: fixed race condition in storage write

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we could mark a line as clean when it should be dirty if we lose a
race condition between storage thread and writer
This commit is contained in:
Andrew Tridgell 2020-04-20 18:20:54 +10:00
parent 0c1ba48212
commit e126b6d346
2 changed files with 35 additions and 12 deletions
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43
libraries/AP_HAL_ChibiOS/Storage.cpp
View File

@ -172,6 +172,7 @@ void Storage::write_block(uint16_t loc, const void *src, size_t n)
}
if (memcmp(src, &_buffer[loc], n) != 0) {
_storage_open();
WITH_SEMAPHORE(sem);
memcpy(&_buffer[loc], src, n);
_mark_dirty(loc, n);
}
@ -200,12 +201,19 @@ void Storage::_timer_tick(void)
return;
}
{
// take a copy of the line we are writing with a semaphore held
WITH_SEMAPHORE(sem);
memcpy(tmpline, &_buffer[CH_STORAGE_LINE_SIZE*i], CH_STORAGE_LINE_SIZE);
}
bool write_ok = false;
#if HAL_WITH_RAMTRON
if (_initialisedType == StorageBackend::FRAM) {
if (fram.write(CH_STORAGE_LINE_SIZE*i, &_buffer[CH_STORAGE_LINE_SIZE*i], CH_STORAGE_LINE_SIZE)) {
_dirty_mask.clear(i);
if (fram.write(CH_STORAGE_LINE_SIZE*i, tmpline, CH_STORAGE_LINE_SIZE)) {
write_ok = true;
}
return;
}
#endif
@ -221,17 +229,31 @@ void Storage::_timer_tick(void)
if (AP::FS().fsync(log_fd) != 0) {
return;
}
_dirty_mask.clear(i);
return;
write_ok = true;
}
#endif
#ifdef STORAGE_FLASH_PAGE
if (_initialisedType == StorageBackend::Flash) {
// save to storage backend
_flash_write(i);
if (_flash_write(i)) {
write_ok = true;
}
}
#endif
if (write_ok) {
WITH_SEMAPHORE(sem);
// while holding the semaphore we check if the copy of the
// line is different from the original line. If it is
// different then someone has re-dirtied the line while we
// were writing it, in which case we should not mark it
// clean. If it matches then we know we can mark the line as
// clean
if (memcmp(tmpline, &_buffer[CH_STORAGE_LINE_SIZE*i], CH_STORAGE_LINE_SIZE) == 0) {
_dirty_mask.clear(i);
}
}
}
/*
@ -255,13 +277,12 @@ void Storage::_flash_load(void)
/*
write one storage line. This also updates _dirty_mask.
*/
void Storage::_flash_write(uint16_t line)
bool Storage::_flash_write(uint16_t line)
{
#ifdef STORAGE_FLASH_PAGE
if (_flash.write(line*CH_STORAGE_LINE_SIZE, CH_STORAGE_LINE_SIZE)) {
// mark the line clean
_dirty_mask.clear(line);
}
return _flash.write(line*CH_STORAGE_LINE_SIZE, CH_STORAGE_LINE_SIZE);
#else
return false;
#endif
}

4
libraries/AP_HAL_ChibiOS/Storage.h
View File

@ -61,6 +61,8 @@ private:
void _mark_dirty(uint16_t loc, uint16_t length);
uint8_t _buffer[CH_STORAGE_SIZE] __attribute__((aligned(4)));
Bitmask<CH_STORAGE_NUM_LINES> _dirty_mask;
HAL_Semaphore sem;
uint8_t tmpline[CH_STORAGE_LINE_SIZE];
bool _flash_write_data(uint8_t sector, uint32_t offset, const uint8_t *data, uint16_t length);
bool _flash_read_data(uint8_t sector, uint32_t offset, uint8_t *data, uint16_t length);
@ -81,7 +83,7 @@ private:
#endif
void _flash_load(void);
void _flash_write(uint16_t line);
bool _flash_write(uint16_t line);
#if HAL_WITH_RAMTRON
AP_RAMTRON fram;