| Message ID | 1428357513-16856-1-git-send-email-kamal@canonical.com |
|---|---|
| State | New |
| Headers | show |
diff --git a/drivers/spi/spi-pl022.c b/drivers/spi/spi-pl022.c index 971855e..fe091a8 100644 --- a/drivers/spi/spi-pl022.c +++ b/drivers/spi/spi-pl022.c @@ -503,12 +503,12 @@ static void giveback(struct pl022 *pl022) pl022->cur_msg = NULL; pl022->cur_transfer = NULL; pl022->cur_chip = NULL; - spi_finalize_current_message(pl022->master); /* disable the SPI/SSP operation */ writew((readw(SSP_CR1(pl022->virtbase)) & (~SSP_CR1_MASK_SSE)), SSP_CR1(pl022->virtbase)); + spi_finalize_current_message(pl022->master); } /**
This is a note to let you know that I have just added a patch titled spi: pl022: Fix race in giveback() leading to driver lock-up to the linux-3.13.y-queue branch of the 3.13.y-ckt extended stable tree which can be found at: http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.13.y-queue This patch is scheduled to be released in version 3.13.11-ckt19. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.13.y-ckt tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Kamal ------ From 0bf2ffdbef52ddb05d0c7ab098452fbc3f76f002 Mon Sep 17 00:00:00 2001 From: Alexander Sverdlin <alexander.sverdlin@nokia.com> Date: Fri, 27 Feb 2015 16:30:21 +0100 Subject: spi: pl022: Fix race in giveback() leading to driver lock-up commit cd6fa8d2ca53cac3226fdcffcf763be390abae32 upstream. Commit fd316941c ("spi/pl022: disable port when unused") introduced a race, which leads to possible driver lock up (easily reproducible on SMP). The problem happens in giveback() function where the completion of the transfer is signalled to SPI subsystem and then the HW SPI controller is disabled. Another transfer might be setup in between, which brings driver in locked-up state. Exact event sequence on SMP: core0 core1 => pump_transfers() /* message->state == STATE_DONE */ => giveback() => spi_finalize_current_message() => pl022_unprepare_transfer_hardware() => pl022_transfer_one_message => flush() => do_interrupt_dma_transfer() => set_up_next_transfer() /* Enable SSP, turn on interrupts */ writew((readw(SSP_CR1(pl022->virtbase)) | SSP_CR1_MASK_SSE), SSP_CR1(pl022->virtbase)); ... => pl022_interrupt_handler() => readwriter() /* disable the SPI/SSP operation */ => writew((readw(SSP_CR1(pl022->virtbase)) & (~SSP_CR1_MASK_SSE)), SSP_CR1(pl022->virtbase)); Lockup! SPI controller is disabled and the data will never be received. Whole SPI subsystem is waiting for transfer ACK and blocked. So, only signal transfer completion after disabling the controller. Fixes: fd316941c (spi/pl022: disable port when unused) Signed-off-by: Alexander Sverdlin <alexander.sverdlin@nokia.com> Signed-off-by: Mark Brown <broonie@kernel.org> Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- drivers/spi/spi-pl022.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) -- 1.9.1