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Message-ID: <1056c115-797c-d121-4623-3b1004032992@redhat.com>
Date: Thu, 9 Feb 2017 07:44:48 -0800
From: Laura Abbott <labbott@...hat.com>
To: "Maciej S. Szmigiero" <mail@...iej.szmigiero.name>,
Evgeniy Polyakov <zbr@...emap.net>
Cc: linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] w1: ds2490: USB transfer buffers need to be DMAable
On 01/18/2017 12:31 PM, Maciej S. Szmigiero wrote:
> ds2490 driver was doing USB transfers from / to buffers on a stack.
> This is not permitted and made the driver non-working with vmapped stacks.
>
> Since all these transfers are done under the same bus_mutex lock we can
> simply use shared buffers in a device private structure for two most common
> of them.
>
> While we are at it, let's also fix a comparison between int and size_t in
> ds9490r_search() which made the driver spin in this function if state
> register get requests were failing.
>
> Signed-off-by: Maciej S. Szmigiero <mail@...iej.szmigiero.name>
> Cc: stable@...r.kernel.org
FWIW, Fedora got a bug report and the reporter there said the patch
worked
https://bugzilla.redhat.com/show_bug.cgi?id=1415397
> ---
> drivers/w1/masters/ds2490.c | 142 ++++++++++++++++++++++++++------------------
> 1 file changed, 84 insertions(+), 58 deletions(-)
>
> diff --git a/drivers/w1/masters/ds2490.c b/drivers/w1/masters/ds2490.c
> index 049a884a756f..59d74d1b47a8 100644
> --- a/drivers/w1/masters/ds2490.c
> +++ b/drivers/w1/masters/ds2490.c
> @@ -153,6 +153,9 @@ struct ds_device
> */
> u16 spu_bit;
>
> + u8 st_buf[ST_SIZE];
> + u8 byte_buf;
> +
> struct w1_bus_master master;
> };
>
> @@ -174,7 +177,6 @@ struct ds_status
> u8 data_in_buffer_status;
> u8 reserved1;
> u8 reserved2;
> -
> };
>
> static struct usb_device_id ds_id_table [] = {
> @@ -244,28 +246,6 @@ static int ds_send_control(struct ds_device *dev, u16 value, u16 index)
> return err;
> }
>
> -static int ds_recv_status_nodump(struct ds_device *dev, struct ds_status *st,
> - unsigned char *buf, int size)
> -{
> - int count, err;
> -
> - memset(st, 0, sizeof(*st));
> -
> - count = 0;
> - err = usb_interrupt_msg(dev->udev, usb_rcvintpipe(dev->udev,
> - dev->ep[EP_STATUS]), buf, size, &count, 1000);
> - if (err < 0) {
> - pr_err("Failed to read 1-wire data from 0x%x: err=%d.\n",
> - dev->ep[EP_STATUS], err);
> - return err;
> - }
> -
> - if (count >= sizeof(*st))
> - memcpy(st, buf, sizeof(*st));
> -
> - return count;
> -}
> -
> static inline void ds_print_msg(unsigned char *buf, unsigned char *str, int off)
> {
> pr_info("%45s: %8x\n", str, buf[off]);
> @@ -324,6 +304,35 @@ static void ds_dump_status(struct ds_device *dev, unsigned char *buf, int count)
> }
> }
>
> +static int ds_recv_status(struct ds_device *dev, struct ds_status *st,
> + bool dump)
> +{
> + int count, err;
> +
> + if (st)
> + memset(st, 0, sizeof(*st));
> +
> + count = 0;
> + err = usb_interrupt_msg(dev->udev,
> + usb_rcvintpipe(dev->udev,
> + dev->ep[EP_STATUS]),
> + dev->st_buf, sizeof(dev->st_buf),
> + &count, 1000);
> + if (err < 0) {
> + pr_err("Failed to read 1-wire data from 0x%x: err=%d.\n",
> + dev->ep[EP_STATUS], err);
> + return err;
> + }
> +
> + if (dump)
> + ds_dump_status(dev, dev->st_buf, count);
> +
> + if (st && count >= sizeof(*st))
> + memcpy(st, dev->st_buf, sizeof(*st));
> +
> + return count;
> +}
> +
> static void ds_reset_device(struct ds_device *dev)
> {
> ds_send_control_cmd(dev, CTL_RESET_DEVICE, 0);
> @@ -344,7 +353,6 @@ static void ds_reset_device(struct ds_device *dev)
> static int ds_recv_data(struct ds_device *dev, unsigned char *buf, int size)
> {
> int count, err;
> - struct ds_status st;
>
> /* Careful on size. If size is less than what is available in
> * the input buffer, the device fails the bulk transfer and
> @@ -359,14 +367,9 @@ static int ds_recv_data(struct ds_device *dev, unsigned char *buf, int size)
> err = usb_bulk_msg(dev->udev, usb_rcvbulkpipe(dev->udev, dev->ep[EP_DATA_IN]),
> buf, size, &count, 1000);
> if (err < 0) {
> - u8 buf[ST_SIZE];
> - int count;
> -
> pr_info("Clearing ep0x%x.\n", dev->ep[EP_DATA_IN]);
> usb_clear_halt(dev->udev, usb_rcvbulkpipe(dev->udev, dev->ep[EP_DATA_IN]));
> -
> - count = ds_recv_status_nodump(dev, &st, buf, sizeof(buf));
> - ds_dump_status(dev, buf, count);
> + ds_recv_status(dev, NULL, true);
> return err;
> }
>
> @@ -404,7 +407,6 @@ int ds_stop_pulse(struct ds_device *dev, int limit)
> {
> struct ds_status st;
> int count = 0, err = 0;
> - u8 buf[ST_SIZE];
>
> do {
> err = ds_send_control(dev, CTL_HALT_EXE_IDLE, 0);
> @@ -413,7 +415,7 @@ int ds_stop_pulse(struct ds_device *dev, int limit)
> err = ds_send_control(dev, CTL_RESUME_EXE, 0);
> if (err)
> break;
> - err = ds_recv_status_nodump(dev, &st, buf, sizeof(buf));
> + err = ds_recv_status(dev, &st, false);
> if (err)
> break;
>
> @@ -456,18 +458,17 @@ int ds_detect(struct ds_device *dev, struct ds_status *st)
>
> static int ds_wait_status(struct ds_device *dev, struct ds_status *st)
> {
> - u8 buf[ST_SIZE];
> int err, count = 0;
>
> do {
> st->status = 0;
> - err = ds_recv_status_nodump(dev, st, buf, sizeof(buf));
> + err = ds_recv_status(dev, st, false);
> #if 0
> if (err >= 0) {
> int i;
> printk("0x%x: count=%d, status: ", dev->ep[EP_STATUS], err);
> for (i=0; i<err; ++i)
> - printk("%02x ", buf[i]);
> + printk("%02x ", dev->st_buf[i]);
> printk("\n");
> }
> #endif
> @@ -485,7 +486,7 @@ static int ds_wait_status(struct ds_device *dev, struct ds_status *st)
> * can do something with it).
> */
> if (err > 16 || count >= 100 || err < 0)
> - ds_dump_status(dev, buf, err);
> + ds_dump_status(dev, dev->st_buf, err);
>
> /* Extended data isn't an error. Well, a short is, but the dump
> * would have already told the user that and we can't do anything
> @@ -608,7 +609,6 @@ static int ds_write_byte(struct ds_device *dev, u8 byte)
> {
> int err;
> struct ds_status st;
> - u8 rbyte;
>
> err = ds_send_control(dev, COMM_BYTE_IO | COMM_IM | dev->spu_bit, byte);
> if (err)
> @@ -621,11 +621,11 @@ static int ds_write_byte(struct ds_device *dev, u8 byte)
> if (err)
> return err;
>
> - err = ds_recv_data(dev, &rbyte, sizeof(rbyte));
> + err = ds_recv_data(dev, &dev->byte_buf, 1);
> if (err < 0)
> return err;
>
> - return !(byte == rbyte);
> + return !(byte == dev->byte_buf);
> }
>
> static int ds_read_byte(struct ds_device *dev, u8 *byte)
> @@ -712,7 +712,6 @@ static void ds9490r_search(void *data, struct w1_master *master,
> int err;
> u16 value, index;
> struct ds_status st;
> - u8 st_buf[ST_SIZE];
> int search_limit;
> int found = 0;
> int i;
> @@ -724,7 +723,12 @@ static void ds9490r_search(void *data, struct w1_master *master,
> /* FIFO 128 bytes, bulk packet size 64, read a multiple of the
> * packet size.
> */
> - u64 buf[2*64/8];
> + const size_t bufsize = 2 * 64;
> + u64 *buf;
> +
> + buf = kmalloc(bufsize, GFP_KERNEL);
> + if (!buf)
> + return;
>
> mutex_lock(&master->bus_mutex);
>
> @@ -745,10 +749,9 @@ static void ds9490r_search(void *data, struct w1_master *master,
> do {
> schedule_timeout(jtime);
>
> - if (ds_recv_status_nodump(dev, &st, st_buf, sizeof(st_buf)) <
> - sizeof(st)) {
> + err = ds_recv_status(dev, &st, false);
> + if (err < 0 || err < sizeof(st))
> break;
> - }
>
> if (st.data_in_buffer_status) {
> /* Bulk in can receive partial ids, but when it does
> @@ -758,7 +761,7 @@ static void ds9490r_search(void *data, struct w1_master *master,
> * bulk without first checking if status says there
> * is data to read.
> */
> - err = ds_recv_data(dev, (u8 *)buf, sizeof(buf));
> + err = ds_recv_data(dev, (u8 *)buf, bufsize);
> if (err < 0)
> break;
> for (i = 0; i < err/8; ++i) {
> @@ -794,9 +797,14 @@ static void ds9490r_search(void *data, struct w1_master *master,
> }
> search_out:
> mutex_unlock(&master->bus_mutex);
> + kfree(buf);
> }
>
> #if 0
> +/*
> + * FIXME: if this disabled code is ever used in the future all ds_send_data()
> + * calls must be changed to use a DMAable buffer.
> + */
> static int ds_match_access(struct ds_device *dev, u64 init)
> {
> int err;
> @@ -845,13 +853,12 @@ static int ds_set_path(struct ds_device *dev, u64 init)
>
> static u8 ds9490r_touch_bit(void *data, u8 bit)
> {
> - u8 ret;
> struct ds_device *dev = data;
>
> - if (ds_touch_bit(dev, bit, &ret))
> + if (ds_touch_bit(dev, bit, &dev->byte_buf))
> return 0;
>
> - return ret;
> + return dev->byte_buf;
> }
>
> #if 0
> @@ -866,13 +873,12 @@ static u8 ds9490r_read_bit(void *data)
> {
> struct ds_device *dev = data;
> int err;
> - u8 bit = 0;
>
> - err = ds_touch_bit(dev, 1, &bit);
> + err = ds_touch_bit(dev, 1, &dev->byte_buf);
> if (err)
> return 0;
>
> - return bit & 1;
> + return dev->byte_buf & 1;
> }
> #endif
>
> @@ -887,32 +893,52 @@ static u8 ds9490r_read_byte(void *data)
> {
> struct ds_device *dev = data;
> int err;
> - u8 byte = 0;
>
> - err = ds_read_byte(dev, &byte);
> + err = ds_read_byte(dev, &dev->byte_buf);
> if (err)
> return 0;
>
> - return byte;
> + return dev->byte_buf;
> }
>
> static void ds9490r_write_block(void *data, const u8 *buf, int len)
> {
> struct ds_device *dev = data;
> + u8 *tbuf;
> +
> + if (len <= 0)
> + return;
> +
> + tbuf = kmalloc(len, GFP_KERNEL);
> + if (!tbuf)
> + return;
>
> - ds_write_block(dev, (u8 *)buf, len);
> + memcpy(tbuf, buf, len);
> + ds_write_block(dev, tbuf, len);
> +
> + kfree(tbuf);
> }
>
> static u8 ds9490r_read_block(void *data, u8 *buf, int len)
> {
> struct ds_device *dev = data;
> int err;
> + u8 *tbuf;
>
> - err = ds_read_block(dev, buf, len);
> - if (err < 0)
> + if (len <= 0)
> + return 0;
> +
> + tbuf = kmalloc(len, GFP_KERNEL);
> + if (!tbuf)
> return 0;
>
> - return len;
> + err = ds_read_block(dev, tbuf, len);
> + if (err >= 0)
> + memcpy(buf, tbuf, len);
> +
> + kfree(tbuf);
> +
> + return err >= 0 ? len : 0;
> }
>
> static u8 ds9490r_reset(void *data)
>
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