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spi: Prevent unexpected SPI time out due to arithmetic overflow 

When reading SPI flash as MTD device, the transfer length is
directly passed to the spi driver. If the requested data size
exceeds 512KB, it will cause the time out calculation to
overflow since transfer length is 32-bit unsigned integer.
This issue is resolved by using 64-bit unsigned integer
to perform the arithmetic.

Signed-off-by: Sien Wu <sien.wu@ni.com>
Acked-by: Brad Keryan <brad.keryan@ni.com>
Acked-by: Gratian Crisan <gratian.crisan@ni.com>
Acked-by: Brad Mouring <brad.mouring@ni.com>

Natinst-ReviewBoard-ID 150232
Signed-off-by: Mark Brown <broonie@kernel.org>
This commit is contained in:
Sien Wu 2016-09-01 18:24:29 -05:00 committed by Mark Brown
parent 29b4817d40
commit d0716dde37
1 changed files with 6 additions and 2 deletions
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8
drivers/spi/spi.c
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@ -960,7 +960,7 @@ static int spi_transfer_one_message(struct spi_master *master,
struct spi_transfer *xfer;
bool keep_cs = false;
int ret = 0;
unsigned long ms = 1;
unsigned long long ms = 1;
struct spi_statistics *statm = &master->statistics;
struct spi_statistics *stats = &msg->spi->statistics;
@ -991,9 +991,13 @@ static int spi_transfer_one_message(struct spi_master *master,
if (ret > 0) {
ret = 0;
ms = xfer->len * 8 * 1000 / xfer->speed_hz;
ms = 8LL * 1000LL * xfer->len;
do_div(ms, xfer->speed_hz);
ms += ms + 100; /* some tolerance */
if (ms > UINT_MAX)
ms = UINT_MAX;
ms = wait_for_completion_timeout(&master->xfer_completion,
msecs_to_jiffies(ms));
}