Re: [PATCH] tty: serial: qcom_geni_serial: Fix softlock
From: Julia Lawall
Date: Tue Nov 27 2018 - 03:48:36 EST
Hello,
Since size_t is unsigned, avail will not be less than 0 on line 742.
Perhaps just reorganize the computation on line 740.
julia
---------- Forwarded message ----------
Date: Tue, 27 Nov 2018 16:13:53 +0800
From: kbuild test robot <lkp@xxxxxxxxx>
To: kbuild@xxxxxx
Cc: Julia Lawall <julia.lawall@xxxxxxx>
Subject: Re: [PATCH] tty: serial: qcom_geni_serial: Fix softlock
CC: kbuild-all@xxxxxx
In-Reply-To: <20181127022536.104663-1-ryandcase@xxxxxxxxxxxx>
References: <20181127022536.104663-1-ryandcase@xxxxxxxxxxxx>
TO: Ryan Case <ryandcase@xxxxxxxxxxxx>
CC: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>, Jiri Slaby <jslaby@xxxxxxxx>, Evan Green <evgreen@xxxxxxxxxxxx>, Doug Anderson <dianders@xxxxxxxxxxxx>, linux-kernel@xxxxxxxxxxxxxxx, linux-serial@xxxxxxxxxxxxxxx, Ryan Case <ryandcase@xxxxxxxxxxxx>
CC: Evan Green <evgreen@xxxxxxxxxxxx>, Doug Anderson <dianders@xxxxxxxxxxxx>, linux-kernel@xxxxxxxxxxxxxxx, linux-serial@xxxxxxxxxxxxxxx, Ryan Case <ryandcase@xxxxxxxxxxxx>
Hi Ryan,
Thank you for the patch! Perhaps something to improve:
[auto build test WARNING on tty/tty-testing]
[also build test WARNING on v4.20-rc4 next-20181126]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]
url: https://github.com/0day-ci/linux/commits/Ryan-Case/tty-serial-qcom_geni_serial-Fix-softlock/20181127-102810
base: https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git tty-testing
:::::: branch date: 6 hours ago
:::::: commit date: 6 hours ago
>> drivers/tty/serial/qcom_geni_serial.c:742:5-10: WARNING: Unsigned expression compared with zero: avail < 0
# https://github.com/0day-ci/linux/commit/407559b41ed61fd8c95ebe39539677bc577c7c66
git remote add linux-review https://github.com/0day-ci/linux
git remote update linux-review
git checkout 407559b41ed61fd8c95ebe39539677bc577c7c66
vim +742 drivers/tty/serial/qcom_geni_serial.c
c4f528795 Karthikeyan Ramasubramanian 2018-03-14 712
407559b41 Ryan Case 2018-11-26 713 static void qcom_geni_serial_handle_tx(struct uart_port *uport, bool done,
407559b41 Ryan Case 2018-11-26 714 bool active)
c4f528795 Karthikeyan Ramasubramanian 2018-03-14 715 {
c4f528795 Karthikeyan Ramasubramanian 2018-03-14 716 struct qcom_geni_serial_port *port = to_dev_port(uport, uport);
c4f528795 Karthikeyan Ramasubramanian 2018-03-14 717 struct circ_buf *xmit = &uport->state->xmit;
c4f528795 Karthikeyan Ramasubramanian 2018-03-14 718 size_t avail;
c4f528795 Karthikeyan Ramasubramanian 2018-03-14 719 size_t remaining;
407559b41 Ryan Case 2018-11-26 720 size_t pending;
c4f528795 Karthikeyan Ramasubramanian 2018-03-14 721 int i;
c4f528795 Karthikeyan Ramasubramanian 2018-03-14 722 u32 status;
c4f528795 Karthikeyan Ramasubramanian 2018-03-14 723 unsigned int chunk;
c4f528795 Karthikeyan Ramasubramanian 2018-03-14 724 int tail;
c4f528795 Karthikeyan Ramasubramanian 2018-03-14 725
c4f528795 Karthikeyan Ramasubramanian 2018-03-14 726 status = readl_relaxed(uport->membase + SE_GENI_TX_FIFO_STATUS);
407559b41 Ryan Case 2018-11-26 727
407559b41 Ryan Case 2018-11-26 728 /* Complete the current tx command before taking newly added data */
407559b41 Ryan Case 2018-11-26 729 if (active)
407559b41 Ryan Case 2018-11-26 730 pending = port->cur_tx_remaining;
407559b41 Ryan Case 2018-11-26 731 else
407559b41 Ryan Case 2018-11-26 732 pending = uart_circ_chars_pending(xmit);
407559b41 Ryan Case 2018-11-26 733
407559b41 Ryan Case 2018-11-26 734 /* All data has been transmitted and acknowledged as received */
407559b41 Ryan Case 2018-11-26 735 if (!pending && !status && done) {
c4f528795 Karthikeyan Ramasubramanian 2018-03-14 736 qcom_geni_serial_stop_tx(uport);
c4f528795 Karthikeyan Ramasubramanian 2018-03-14 737 goto out_write_wakeup;
c4f528795 Karthikeyan Ramasubramanian 2018-03-14 738 }
c4f528795 Karthikeyan Ramasubramanian 2018-03-14 739
407559b41 Ryan Case 2018-11-26 740 avail = port->tx_fifo_depth - (status & TX_FIFO_WC);
407559b41 Ryan Case 2018-11-26 741 avail *= port->tx_bytes_pw;
407559b41 Ryan Case 2018-11-26 @742 if (avail < 0)
407559b41 Ryan Case 2018-11-26 743 avail = 0;
8a8a66a1a Girish Mahadevan 2018-07-13 744
638a6f4eb Evan Green 2018-05-09 745 tail = xmit->tail;
407559b41 Ryan Case 2018-11-26 746 chunk = min3((size_t)pending, (size_t)(UART_XMIT_SIZE - tail), avail);
c4f528795 Karthikeyan Ramasubramanian 2018-03-14 747 if (!chunk)
c4f528795 Karthikeyan Ramasubramanian 2018-03-14 748 goto out_write_wakeup;
c4f528795 Karthikeyan Ramasubramanian 2018-03-14 749
407559b41 Ryan Case 2018-11-26 750 if (!port->cur_tx_remaining) {
407559b41 Ryan Case 2018-11-26 751 qcom_geni_serial_setup_tx(uport, pending);
407559b41 Ryan Case 2018-11-26 752 port->cur_tx_remaining = pending;
407559b41 Ryan Case 2018-11-26 753 }
c4f528795 Karthikeyan Ramasubramanian 2018-03-14 754
c4f528795 Karthikeyan Ramasubramanian 2018-03-14 755 remaining = chunk;
c4f528795 Karthikeyan Ramasubramanian 2018-03-14 756 for (i = 0; i < chunk; ) {
c4f528795 Karthikeyan Ramasubramanian 2018-03-14 757 unsigned int tx_bytes;
69736b57d Karthikeyan Ramasubramanian 2018-05-03 758 u8 buf[sizeof(u32)];
c4f528795 Karthikeyan Ramasubramanian 2018-03-14 759 int c;
c4f528795 Karthikeyan Ramasubramanian 2018-03-14 760
69736b57d Karthikeyan Ramasubramanian 2018-05-03 761 memset(buf, 0, ARRAY_SIZE(buf));
6a10635e9 Karthikeyan Ramasubramanian 2018-05-03 762 tx_bytes = min_t(size_t, remaining, port->tx_bytes_pw);
c4f528795 Karthikeyan Ramasubramanian 2018-03-14 763 for (c = 0; c < tx_bytes ; c++)
69736b57d Karthikeyan Ramasubramanian 2018-05-03 764 buf[c] = xmit->buf[tail + c];
c4f528795 Karthikeyan Ramasubramanian 2018-03-14 765
69736b57d Karthikeyan Ramasubramanian 2018-05-03 766 iowrite32_rep(uport->membase + SE_GENI_TX_FIFOn, buf, 1);
c4f528795 Karthikeyan Ramasubramanian 2018-03-14 767
c4f528795 Karthikeyan Ramasubramanian 2018-03-14 768 i += tx_bytes;
638a6f4eb Evan Green 2018-05-09 769 tail += tx_bytes;
c4f528795 Karthikeyan Ramasubramanian 2018-03-14 770 uport->icount.tx += tx_bytes;
c4f528795 Karthikeyan Ramasubramanian 2018-03-14 771 remaining -= tx_bytes;
407559b41 Ryan Case 2018-11-26 772 port->cur_tx_remaining -= tx_bytes;
c4f528795 Karthikeyan Ramasubramanian 2018-03-14 773 }
638a6f4eb Evan Green 2018-05-09 774
638a6f4eb Evan Green 2018-05-09 775 xmit->tail = tail & (UART_XMIT_SIZE - 1);
c4f528795 Karthikeyan Ramasubramanian 2018-03-14 776 out_write_wakeup:
638a6f4eb Evan Green 2018-05-09 777 if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
c4f528795 Karthikeyan Ramasubramanian 2018-03-14 778 uart_write_wakeup(uport);
c4f528795 Karthikeyan Ramasubramanian 2018-03-14 779 }
c4f528795 Karthikeyan Ramasubramanian 2018-03-14 780
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