Patch "spi: ti-qspi: Fix data corruption seen on r/w stress test" has been added to the 4.3-stable tree

Patch "spi: ti-qspi: Fix data corruption seen on r/w stress test" has been added to the 4.3-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    spi: ti-qspi: Fix data corruption seen on r/w stress test

to the 4.3-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     spi-ti-qspi-fix-data-corruption-seen-on-r-w-stress-test.patch
and it can be found in the queue-4.3 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From bc27a53928981662079aa243915b443370294a03 Mon Sep 17 00:00:00 2001
From: Vignesh R <vigneshr@ti.com>
Date: Mon, 12 Oct 2015 13:22:02 +0530
Subject: spi: ti-qspi: Fix data corruption seen on r/w stress test

From: Vignesh R <vigneshr@ti.com>

commit bc27a53928981662079aa243915b443370294a03 upstream.

Writing invalid command to QSPI_SPI_CMD_REG will terminate current
transfer and de-assert the chip select. This has to be done before
calling spi_finalize_current_message(). Because
spi_finalize_current_message() will mark the end of current message
transfer and schedule the next transfer. If the chipselect is not
de-asserted before calling spi_finalize_current_message() then the next
transfer will overlap with the previous transfer leading to data
corruption.
__spi_pump_message() can be called either from kthread worker context or
directly from the calling process's context. It is possible that these
two calls can race against each other. But race is serialized by
checking whether master->cur_msg == NULL (pointer to msg being handled
by transfer_one() at present). The master->cur_msg is set to NULL when
spi_finalize_current_message() is called on that message, which means
calling spi_finalize_current_message() allows __spi_sync() to pump next
message in calling process context.
Now if spi-ti-qspi calls spi_finalize_current_message() before we
terminate transfer at hardware side, if __spi_pump_message() is called
from process context then the successive transactions can overlap.

Fix this by moving writing invalid command to QSPI_SPI_CMD_REG to
before calling spi_finalize_current_message() call.

Signed-off-by: Vignesh R <vigneshr@ti.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/spi/spi-ti-qspi.c |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

--- a/drivers/spi/spi-ti-qspi.c
+++ b/drivers/spi/spi-ti-qspi.c
@@ -410,11 +410,10 @@ static int ti_qspi_start_transfer_one(st
 
 	mutex_unlock(&qspi->list_lock);
 
+	ti_qspi_write(qspi, qspi->cmd | QSPI_INVAL, QSPI_SPI_CMD_REG);
 	m->status = status;
 	spi_finalize_current_message(master);
 
-	ti_qspi_write(qspi, qspi->cmd | QSPI_INVAL, QSPI_SPI_CMD_REG);
-
 	return status;
 }
 


Patches currently in stable-queue which might be from vigneshr@ti.com are

queue-4.3/spi-ti-qspi-fix-data-corruption-seen-on-r-w-stress-test.patch