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Postpone interacting with the web workflow if a SPI bus is locked

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I tested this by fetching a .txt file repeatedly using curl while
running the fancy camera demo. (100+ times without failure). I also
repeatedly loaded the filesystem view http://.../fs/#/sd/ which worked
10+ times without failure, but does take some time (multiple seconds) to
show a listing with a few dozen files.

(I suspect there's an accidentally quadratic behavior in oofatfs to stat
every file in a directory, because it repeatedly does a linear search of
the directory for the stat information of each file, but that's not an
issue for Right Now(TM))

Closes: #8980
This commit is contained in:
Jeff Epler 2024-03-04 20:14:25 -06:00
parent cbdaaea9fb
commit c0064dcf9f
1 changed files with 28 additions and 1 deletions
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29
supervisor/shared/web_workflow/web_workflow.c
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@ -54,6 +54,10 @@
#include "shared-bindings/hashlib/Hash.h"
#include "lib/oofatfs/diskio.h"
#if CIRCUITPY_FOURWIRE
#include "shared-module/displayio/__init__.h"
#endif
#if CIRCUITPY_MDNS
#include "shared-bindings/mdns/RemoteService.h"
#include "shared-bindings/mdns/Server.h"
@ -1559,9 +1563,32 @@ static void _process_request(socketpool_socket_obj_t *socket, _request *request)
}
}
static bool supervisor_filesystem_access_could_block(void) {
#if CIRCUITPY_FOURWIRE
mp_vfs_mount_t *vfs = MP_STATE_VM(vfs_mount_table);
if (!vfs->next) {
// Assume that the CIRCUITPY root is not sharing a SPI bus with the display SPI bus
return false;
}
// Check display 0 to see if it's on a fourwire (SPI) bus. If it is, blocking is possible
// in theory other displays could block but also in reality there's generally 0 or 1 displays
for (size_t i = 0; i < CIRCUITPY_DISPLAY_LIMIT; i++) {
if (display_buses[i].bus_base.type != &fourwire_fourwire_type) {
continue;
}
if (!common_hal_fourwire_fourwire_bus_free(MP_OBJ_FROM_PTR(&display_buses[i].bus_base))) {
return true;
}
}
#endif
return false;
}
void supervisor_web_workflow_background(void *data) {
while (true) {
// If "/sd" is mounted AND shared with a display, access could block.
// We don't have a good way to defer a filesystem action way down inside _process_request
// when this happens, so just postpone if there's a chance of blocking. (#8980)
while (!supervisor_filesystem_access_could_block()) {
// If we have a request in progress, continue working on it. Do this first
// so that we can accept another socket after finishing this request.
if (common_hal_socketpool_socket_get_connected(&active)) {