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drivers/serial/serial.c: only adapt readv api to avoid block on secou…
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…nd read in readv()

Signed-off-by: chao an <[email protected]>
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@anchao
anchao committed Jan 22, 2025
1 parent 6e509ce commit 44d8dcf
Showing 1 changed file with 71 additions and 72 deletions.
143 changes: 71 additions & 72 deletions drivers/serial/serial.c
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Original file line number Diff line number Diff line change
Expand Up @@ -99,8 +99,6 @@ static int uart_putxmitchar(FAR uart_dev_t *dev, int ch,
static inline ssize_t uart_irqwrite(FAR uart_dev_t *dev,
FAR const char *buffer,
size_t buflen);
static inline ssize_t uart_irqwritev(FAR uart_dev_t *dev,
FAR struct uio *uio);
static int uart_tcdrain(FAR uart_dev_t *dev,
bool cancelable, clock_t timeout);

Expand All @@ -112,8 +110,12 @@ static int uart_tcsendbreak(FAR uart_dev_t *dev,

static int uart_open(FAR struct file *filep);
static int uart_close(FAR struct file *filep);
static ssize_t uart_read(FAR struct file *filep,
FAR char *buffer, size_t buflen);
static ssize_t uart_write(FAR struct file *filep,
FAR const char *buffer,
size_t buflen);
static ssize_t uart_readv(FAR struct file *filep, FAR struct uio *uio);
static ssize_t uart_writev(FAR struct file *filep, FAR struct uio *uio);
static int uart_ioctl(FAR struct file *filep,
int cmd, unsigned long arg);
static int uart_poll(FAR struct file *filep,
Expand All @@ -140,15 +142,15 @@ static const struct file_operations g_serialops =
{
uart_open, /* open */
uart_close, /* close */
NULL, /* read */
NULL, /* write */
uart_read, /* read */
uart_write, /* write */
NULL, /* seek */
uart_ioctl, /* ioctl */
NULL, /* mmap */
NULL, /* truncate */
uart_poll, /* poll */
uart_readv, /* readv */
uart_writev /* writev */
NULL /* writev */
#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
, uart_unlink /* unlink */
#endif
Expand Down Expand Up @@ -440,50 +442,6 @@ static inline ssize_t uart_irqwrite(FAR uart_dev_t *dev,
return buflen;
}

/****************************************************************************
* Name: uart_irqwritev
****************************************************************************/

static inline ssize_t uart_irqwritev(FAR uart_dev_t *dev,
FAR struct uio *uio)
{
ssize_t error = 0;
ssize_t total = 0;
int iovcnt = uio->uio_iovcnt;
int i;

for (i = 0; i < iovcnt; i++)
{
const struct iovec *iov = &uio->uio_iov[i];
if (iov->iov_len == 0)
{
continue;
}

ssize_t written = uart_irqwrite(dev, iov->iov_base, iov->iov_len);
if (written < 0)
{
error = written;
break;
}

if (SSIZE_MAX - total < written)
{
error = -EOVERFLOW;
break;
}

total += written;
}

if (error != 0 && total == 0)
{
return error;
}

return total;
}

/****************************************************************************
* Name: uart_tcdrain
*
Expand Down Expand Up @@ -890,10 +848,11 @@ static int uart_close(FAR struct file *filep)
}

/****************************************************************************
* Name: uart_readv
* Name: uart_read
****************************************************************************/

static ssize_t uart_readv(FAR struct file *filep, FAR struct uio *uio)
static ssize_t uart_read_internal(FAR struct file *filep, FAR char *buffer,
size_t buflen, bool nonblock)
{
FAR struct inode *inode = filep->f_inode;
FAR uart_dev_t *dev = inode->i_private;
Expand All @@ -904,7 +863,6 @@ static ssize_t uart_readv(FAR struct file *filep, FAR struct uio *uio)
#endif
irqstate_t flags;
ssize_t recvd = 0;
ssize_t buflen;
bool echoed = false;
int16_t tail;
char ch;
Expand All @@ -928,8 +886,7 @@ static ssize_t uart_readv(FAR struct file *filep, FAR struct uio *uio)
* data from the end of the buffer.
*/

buflen = uio->uio_resid;
while (recvd < buflen)
while ((size_t)recvd < buflen)
{
#ifdef CONFIG_SERIAL_REMOVABLE
/* If the removable device is no longer connected, refuse to read any
Expand Down Expand Up @@ -1005,8 +962,7 @@ static ssize_t uart_readv(FAR struct file *filep, FAR struct uio *uio)
{
if (recvd > 0)
{
static const char zero = '\0';
uio_copyfrom(uio, recvd, &zero, 1);
*buffer-- = '\0';
recvd--;
if (dev->tc_lflag & ECHO)
{
Expand Down Expand Up @@ -1035,7 +991,7 @@ static ssize_t uart_readv(FAR struct file *filep, FAR struct uio *uio)

/* Store the received character */

uio_copyfrom(uio, recvd, &ch, 1);
*buffer++ = ch;
recvd++;

if (dev->tc_lflag & ECHO)
Expand Down Expand Up @@ -1105,7 +1061,7 @@ static ssize_t uart_readv(FAR struct file *filep, FAR struct uio *uio)
* return what we have.
*/

else if ((filep->f_oflags & O_NONBLOCK) != 0)
else if ((filep->f_oflags & O_NONBLOCK) != 0 || nonblock)
{
/* If nothing was transferred, then return the -EAGAIN
* error (not zero which means end of file).
Expand Down Expand Up @@ -1147,7 +1103,7 @@ static ssize_t uart_readv(FAR struct file *filep, FAR struct uio *uio)
* wait.
*/

else if ((filep->f_oflags & O_NONBLOCK) != 0)
else if ((filep->f_oflags & O_NONBLOCK) != 0 || nonblock)
{
/* Break out of the loop returning -EAGAIN */

Expand Down Expand Up @@ -1370,24 +1326,69 @@ static ssize_t uart_readv(FAR struct file *filep, FAR struct uio *uio)
#endif

nxmutex_unlock(&dev->recv.lock);
if (recvd >= 0)
return recvd;
}

static ssize_t uart_read(FAR struct file *filep,
FAR char *buffer, size_t buflen)
{
return uart_read_internal(filep, buffer, buflen, false);
}

/****************************************************************************
* Name: uart_readv
****************************************************************************/

static ssize_t uart_readv(FAR struct file *filep, FAR struct uio *uio)
{
FAR const struct iovec *iov = uio->uio_iov;
int iovcnt = uio->uio_iovcnt;
bool nonblock = !!(filep->f_oflags & O_NONBLOCK);
ssize_t ntotal;
ssize_t nread;
int i;

for (i = 0, ntotal = 0; i < iovcnt; i++)
{
uio_advance(uio, recvd);
nread = uart_read_internal(filep, iov[i].iov_base,
iov[i].iov_len, nonblock);
if (nread < 0)
{
if (ntotal > 0)
{
break;
}

return nread;
}

ntotal += nread;

/* Check for a parital success condition, including an end-of-file */

if (nread < iov[i].iov_len)
{
break;
}

/* set nonblock flag after first read */

nonblock = true;
}

return recvd;
return ntotal;
}

/****************************************************************************
* Name: uart_writev
* Name: uart_write
****************************************************************************/

static ssize_t uart_writev(FAR struct file *filep, FAR struct uio *uio)
static ssize_t uart_write(FAR struct file *filep, FAR const char *buffer,
size_t buflen)
{
FAR struct inode *inode = filep->f_inode;
FAR uart_dev_t *dev = inode->i_private;
ssize_t nwritten;
ssize_t buflen;
ssize_t nwritten = buflen;
bool oktoblock;
int ret;
char ch;
Expand All @@ -1413,14 +1414,12 @@ static ssize_t uart_writev(FAR struct file *filep, FAR struct uio *uio)
#endif

flags = enter_critical_section();
ret = uart_irqwritev(dev, uio);
ret = uart_irqwrite(dev, buffer, buflen);
leave_critical_section(flags);

return ret;
}

buflen = nwritten = uio->uio_resid;

/* Only one user can access dev->xmit.head at a time */

ret = nxmutex_lock(&dev->xmit.lock);
Expand Down Expand Up @@ -1460,9 +1459,9 @@ static ssize_t uart_writev(FAR struct file *filep, FAR struct uio *uio)
*/

uart_disabletxint(dev);
for (; buflen; uio_advance(uio, 1), buflen--)
for (; buflen; buflen--)
{
uio_copyto(uio, 0, &ch, 1);
ch = *buffer++;
ret = OK;

/* Do output post-processing */
Expand Down

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