6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx> [ Upstream commit 30c9ae5ece8ecd69d36e6912c2c0896418f2468c ] Treat each completed full size write to /dev/ttyDBC0 as a separate usb transfer. Make sure the size of the TRBs matches the size of the tty write by first queuing as many max packet size TRBs as possible up to the last TRB which will be cut short to match the size of the tty write. This solves an issue where userspace writes several transfers back to back via /dev/ttyDBC0 into a kfifo before dbgtty can find available request to turn that kfifo data into TRBs on the transfer ring. The boundary between transfer was lost as xhci-dbgtty then turned everyting in the kfifo into as many 'max packet size' TRBs as possible. DbC would then send more data to the host than intended for that transfer, causing host to issue a babble error. Refuse to write more data to kfifo until previous tty write data is turned into properly sized TRBs with data size boundaries matching tty write size Tested-by: Uday M Bhat <uday.m.bhat@xxxxxxxxx> Tested-by: Łukasz Bartosik <ukaszb@xxxxxxxxxxxx> Cc: stable@xxxxxxxxxxxxxxx Signed-off-by: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx> Link: https://lore.kernel.org/r/20241016140000.783905-5-mathias.nyman@xxxxxxxxxxxxxxx Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- drivers/usb/host/xhci-dbgcap.h | 1 + drivers/usb/host/xhci-dbgtty.c | 55 ++++++++++++++++++++++++++++++---- 2 files changed, 51 insertions(+), 5 deletions(-) diff --git a/drivers/usb/host/xhci-dbgcap.h b/drivers/usb/host/xhci-dbgcap.h index 0d4d60758af97..caeadfb8760b6 100644 --- a/drivers/usb/host/xhci-dbgcap.h +++ b/drivers/usb/host/xhci-dbgcap.h @@ -108,6 +108,7 @@ struct dbc_port { struct tasklet_struct push; struct list_head write_pool; + unsigned int tx_boundary; bool registered; }; diff --git a/drivers/usb/host/xhci-dbgtty.c b/drivers/usb/host/xhci-dbgtty.c index f6e25a1cec115..6dd7e8c8eed08 100644 --- a/drivers/usb/host/xhci-dbgtty.c +++ b/drivers/usb/host/xhci-dbgtty.c @@ -24,6 +24,29 @@ static inline struct dbc_port *dbc_to_port(struct xhci_dbc *dbc) return dbc->priv; } +static unsigned int +dbc_kfifo_to_req(struct dbc_port *port, char *packet) +{ + unsigned int len; + + len = kfifo_len(&port->port.xmit_fifo); + + if (len == 0) + return 0; + + len = min(len, DBC_MAX_PACKET); + + if (port->tx_boundary) + len = min(port->tx_boundary, len); + + len = kfifo_out(&port->port.xmit_fifo, packet, len); + + if (port->tx_boundary) + port->tx_boundary -= len; + + return len; +} + static int dbc_start_tx(struct dbc_port *port) __releases(&port->port_lock) __acquires(&port->port_lock) @@ -36,7 +59,7 @@ static int dbc_start_tx(struct dbc_port *port) while (!list_empty(pool)) { req = list_entry(pool->next, struct dbc_request, list_pool); - len = kfifo_out(&port->port.xmit_fifo, req->buf, DBC_MAX_PACKET); + len = dbc_kfifo_to_req(port, req->buf); if (len == 0) break; do_tty_wake = true; @@ -201,14 +224,32 @@ static int dbc_tty_write(struct tty_struct *tty, { struct dbc_port *port = tty->driver_data; unsigned long flags; + unsigned int written = 0; spin_lock_irqsave(&port->port_lock, flags); - if (count) - count = kfifo_in(&port->port.xmit_fifo, buf, count); - dbc_start_tx(port); + + /* + * Treat tty write as one usb transfer. Make sure the writes are turned + * into TRB request having the same size boundaries as the tty writes. + * Don't add data to kfifo before previous write is turned into TRBs + */ + if (port->tx_boundary) { + spin_unlock_irqrestore(&port->port_lock, flags); + return 0; + } + + if (count) { + written = kfifo_in(&port->port.xmit_fifo, buf, count); + + if (written == count) + port->tx_boundary = kfifo_len(&port->port.xmit_fifo); + + dbc_start_tx(port); + } + spin_unlock_irqrestore(&port->port_lock, flags); - return count; + return written; } static int dbc_tty_put_char(struct tty_struct *tty, unsigned char ch) @@ -242,6 +283,10 @@ static unsigned int dbc_tty_write_room(struct tty_struct *tty) spin_lock_irqsave(&port->port_lock, flags); room = kfifo_avail(&port->port.xmit_fifo); + + if (port->tx_boundary) + room = 0; + spin_unlock_irqrestore(&port->port_lock, flags); return room; -- 2.43.0
