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usb storage: defer commands until exclusive storage handover completes

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A host may send a command after SET_CONFIGURATION while filesystem clients are still acknowledging the storage handover. Previously TEST UNIT READY could report no medium, while other commands could reach storage before exclusive access was granted.

Retain the first CBW until exclusive access is available. Notify the mass-storage class when handover completes, then execute the retained command and keep the OUT endpoint unarmed until its CSW. On BOT reset, discard the retained CBW and accept a new command.

This changes command handling while waiting for ownership. The policy for requesting, preserving and releasing exclusive storage is handled by a separate preparatory patch.

Change-Id: If82fc87160e9d7da930a3217445fea92e58dd1ec
This commit is contained in:
Paul Sauro 2026-09-21 00:17:29 +02:00
parent 2b664d6025
commit e2ee665cce
2 changed files with 38 additions and 8 deletions
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40
firmware/usbstack/usb_storage.c
View file

@ -351,6 +351,7 @@ static unsigned char* ramdisk_buffer;
static enum {
WAITING_FOR_COMMAND,
WAITING_FOR_STORAGE,
SENDING_BLOCKS,
SENDING_RESULT,
SENDING_FAILED_RESULT,
@ -520,6 +521,9 @@ static void usb_storage_transfer_complete(int ep,int dir,int status,int length)
account_data_transfer(dir, status, length);
switch(state) {
case WAITING_FOR_STORAGE:
/* The CBW is retained until usb_storage_notify_event(). */
break;
case RECEIVING_BLOCKS:
if(dir==USB_DIR_IN) {
logf("IN received in RECEIVING");
@ -734,6 +738,11 @@ static bool usb_storage_control_request(struct usb_ctrlrequest* req, uint8_t* re
case USB_BULK_RESET_REQUEST:
logf("ums: bulk reset");
if(state == WAITING_FOR_STORAGE) {
/* Discard the retained CBW on host reset and accept a new
* one; do not replay the cancelled command when ready. */
usb_drv_recv_nonblocking(EP_OUT, cbw_buffer, MAX_CBW_SIZE);
}
state = WAITING_FOR_COMMAND;
/* UMS BOT 3.1 says The device shall preserve the value of its bulk
data toggle bits and endpoint STALL conditions despite
@ -786,7 +795,7 @@ static void send_and_read_next(void)
}
/****************************************************************************/
static void handle_scsi(struct command_block_wrapper* cbw)
static void handle_scsi_ready(struct command_block_wrapper* cbw)
{
struct storage_info info;
unsigned int length = cbw->data_transfer_length;
@ -841,13 +850,6 @@ static void handle_scsi(struct command_block_wrapper* cbw)
switch (cbw->command_block[0]) {
case SCSI_TEST_UNIT_READY:
logf("scsi test_unit_ready %d",lun);
if(!usb_exclusive_storage()) {
send_csw(UMS_STATUS_FAIL);
cur_sense_data.sense_key=SENSE_NOT_READY;
cur_sense_data.asc=ASC_MEDIUM_NOT_PRESENT;
cur_sense_data.ascq=0;
break;
}
if(lun_present) {
send_csw(UMS_STATUS_GOOD);
}
@ -1424,6 +1426,27 @@ static void handle_scsi(struct command_block_wrapper* cbw)
}
}
/* SET_CONFIGURATION now precedes the storage handover. Keep the first
* CBW pending until all Rockbox clients have acknowledged/unmounted. This
* avoids falsely reporting an absent disk to a fast host and, importantly,
* prevents READ/WRITE commands from racing Rockbox filesystem users. The
* OUT endpoint is not rearmed until this CBW has received its CSW. */
static void handle_scsi(struct command_block_wrapper* cbw)
{
if(!usb_exclusive_storage()) {
state = WAITING_FOR_STORAGE;
return;
}
handle_scsi_ready(cbw);
}
static void usb_storage_notify_event(intptr_t data)
{
(void)data;
if(state == WAITING_FOR_STORAGE && usb_exclusive_storage())
handle_scsi((struct command_block_wrapper*)cbw_buffer);
}
/* Count data only, never the CBW or CSW. A short result must report the
* untransferred bytes instead of claiming that the whole request succeeded. */
static void account_data_transfer(int dir, int status, int length)
@ -1554,6 +1577,7 @@ struct usb_class_driver usb_cdrv_storage = {
.disconnect = usb_storage_disconnect,
.transfer_complete = usb_storage_transfer_complete,
.control_request = usb_storage_control_request,
.notify_event = usb_storage_notify_event,
#ifdef HAVE_HOTSWAP
.notify_hotswap = usb_storage_notify_hotswap,
#endif