From: Vladimir Oltean vladimir.oltean@nxp.com
[ Upstream commit 4f5ee75ea1718a09149460b3df993f389a67b56a ]
Currently the driver puts the process in interruptible sleep waiting for the interrupt train to finish transfer to/from the tx_buf and rx_buf.
But exiting the process with ctrl-c may make the kernel panic: the wait_event_interruptible call will return -ERESTARTSYS, which a proper driver implementation is perhaps supposed to handle, but nonetheless this one doesn't, and aborts the transfer altogether.
Actually when the task is interrupted, there is still a high chance that the dspi_interrupt is still triggering. And if dspi_transfer_one_message returns execution all the way to the spi_device driver, that can free the spi_message and spi_transfer structures, leaving the interrupts to access a freed tx_buf and rx_buf.
hexdump -C /dev/mtd0 00000000 00 75 68 75 0a ff ff ff ff ff ff ff ff ff ff ff |.uhu............| 00000010 ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff |................| * ^C[ 38.495955] fsl-dspi 2120000.spi: Waiting for transfer to complete failed! [ 38.503097] spi_master spi2: failed to transfer one message from queue [ 38.509729] Unable to handle kernel paging request at virtual address ffff800095ab3377 [ 38.517676] Mem abort info: [ 38.520474] ESR = 0x96000045 [ 38.523533] EC = 0x25: DABT (current EL), IL = 32 bits [ 38.528861] SET = 0, FnV = 0 [ 38.531921] EA = 0, S1PTW = 0 [ 38.535067] Data abort info: [ 38.537952] ISV = 0, ISS = 0x00000045 [ 38.541797] CM = 0, WnR = 1 [ 38.544771] swapper pgtable: 4k pages, 48-bit VAs, pgdp=0000000082621000 [ 38.551494] [ffff800095ab3377] pgd=00000020fffff003, p4d=00000020fffff003, pud=0000000000000000 [ 38.560229] Internal error: Oops: 96000045 [#1] PREEMPT SMP [ 38.565819] Modules linked in: [ 38.568882] CPU: 0 PID: 2729 Comm: hexdump Not tainted 5.6.0-rc4-next-20200306-00052-gd8730cdc8a0b-dirty #193 [ 38.578834] Hardware name: Kontron SMARC-sAL28 (Single PHY) on SMARC Eval 2.0 carrier (DT) [ 38.587129] pstate: 20000085 (nzCv daIf -PAN -UAO) [ 38.591941] pc : ktime_get_real_ts64+0x3c/0x110 [ 38.596487] lr : spi_take_timestamp_pre+0x40/0x90 [ 38.601203] sp : ffff800010003d90 [ 38.604525] x29: ffff800010003d90 x28: ffff80001200e000 [ 38.609854] x27: ffff800011da9000 x26: ffff002079c40400 [ 38.615184] x25: ffff8000117fe018 x24: ffff800011daa1a0 [ 38.620513] x23: ffff800015ab3860 x22: ffff800095ab3377 [ 38.625841] x21: 000000000000146e x20: ffff8000120c3000 [ 38.631170] x19: ffff0020795f6e80 x18: ffff800011da9948 [ 38.636498] x17: 0000000000000000 x16: 0000000000000000 [ 38.641826] x15: ffff800095ab3377 x14: 0720072007200720 [ 38.647155] x13: 0720072007200765 x12: 0775076507750771 [ 38.652483] x11: 0720076d076f0772 x10: 0000000000000040 [ 38.657812] x9 : ffff8000108e2100 x8 : ffff800011dcabe8 [ 38.663139] x7 : 0000000000000000 x6 : ffff800015ab3a60 [ 38.668468] x5 : 0000000007200720 x4 : ffff800095ab3377 [ 38.673796] x3 : 0000000000000000 x2 : 0000000000000ab0 [ 38.679125] x1 : ffff800011daa000 x0 : 0000000000000026 [ 38.684454] Call trace: [ 38.686905] ktime_get_real_ts64+0x3c/0x110 [ 38.691100] spi_take_timestamp_pre+0x40/0x90 [ 38.695470] dspi_fifo_write+0x58/0x2c0 [ 38.699315] dspi_interrupt+0xbc/0xd0 [ 38.702987] __handle_irq_event_percpu+0x78/0x2c0 [ 38.707706] handle_irq_event_percpu+0x3c/0x90 [ 38.712161] handle_irq_event+0x4c/0xd0 [ 38.716008] handle_fasteoi_irq+0xbc/0x170 [ 38.720115] generic_handle_irq+0x2c/0x40 [ 38.724135] __handle_domain_irq+0x68/0xc0 [ 38.728243] gic_handle_irq+0xc8/0x160 [ 38.732000] el1_irq+0xb8/0x180 [ 38.735149] spi_nor_spimem_read_data+0xe0/0x140 [ 38.739779] spi_nor_read+0xc4/0x120 [ 38.743364] mtd_read_oob+0xa8/0xc0 [ 38.746860] mtd_read+0x4c/0x80 [ 38.750007] mtdchar_read+0x108/0x2a0 [ 38.753679] __vfs_read+0x20/0x50 [ 38.757002] vfs_read+0xa4/0x190 [ 38.760237] ksys_read+0x6c/0xf0 [ 38.763471] __arm64_sys_read+0x20/0x30 [ 38.767319] el0_svc_common.constprop.3+0x90/0x160 [ 38.772125] do_el0_svc+0x28/0x90 [ 38.775449] el0_sync_handler+0x118/0x190 [ 38.779468] el0_sync+0x140/0x180 [ 38.782793] Code: 91000294 1400000f d50339bf f9405e80 (f90002c0) [ 38.788910] ---[ end trace 55da560db4d6bef7 ]--- [ 38.793540] Kernel panic - not syncing: Fatal exception in interrupt [ 38.799914] SMP: stopping secondary CPUs [ 38.803849] Kernel Offset: disabled [ 38.807344] CPU features: 0x10002,20006008 [ 38.811451] Memory Limit: none [ 38.814513] ---[ end Kernel panic - not syncing: Fatal exception in interrupt ]---
So it is clear that the "interruptible" part isn't handled correctly. When the process receives a signal, one could either attempt a clean abort (which appears to be difficult with this hardware) or just keep restarting the sleep until the wait queue really completes. But checking in a loop for -ERESTARTSYS is a bit too complicated for this driver, so just make the sleep uninterruptible, to avoid all that nonsense.
The wait queue was actually restructured as a completion, after polling other drivers for the most "popular" approach.
Fixes: 349ad66c0ab0 ("spi:Add Freescale DSPI driver for Vybrid VF610 platform") Reported-by: Michael Walle michael@walle.cc Signed-off-by: Vladimir Oltean vladimir.oltean@nxp.com Tested-by: Michael Walle michael@walle.cc Link: https://lore.kernel.org/r/20200318001603.9650-7-olteanv@gmail.com Signed-off-by: Mark Brown broonie@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/spi/spi-fsl-dspi.c | 19 ++++++------------- 1 file changed, 6 insertions(+), 13 deletions(-)
diff --git a/drivers/spi/spi-fsl-dspi.c b/drivers/spi/spi-fsl-dspi.c index d47bd26577b37..68e33457c814f 100644 --- a/drivers/spi/spi-fsl-dspi.c +++ b/drivers/spi/spi-fsl-dspi.c @@ -192,8 +192,7 @@ struct fsl_dspi { u8 bytes_per_word; const struct fsl_dspi_devtype_data *devtype_data;
- wait_queue_head_t waitq; - u32 waitflags; + struct completion xfer_done;
struct fsl_dspi_dma *dma; }; @@ -703,10 +702,8 @@ static irqreturn_t dspi_interrupt(int irq, void *dev_id) if (!(spi_sr & (SPI_SR_EOQF | SPI_SR_TCFQF))) return IRQ_NONE;
- if (dspi_rxtx(dspi) == 0) { - dspi->waitflags = 1; - wake_up_interruptible(&dspi->waitq); - } + if (dspi_rxtx(dspi) == 0) + complete(&dspi->xfer_done);
return IRQ_HANDLED; } @@ -800,13 +797,9 @@ static int dspi_transfer_one_message(struct spi_controller *ctlr, status = dspi_poll(dspi); } while (status == -EINPROGRESS); } else if (trans_mode != DSPI_DMA_MODE) { - status = wait_event_interruptible(dspi->waitq, - dspi->waitflags); - dspi->waitflags = 0; + wait_for_completion(&dspi->xfer_done); + reinit_completion(&dspi->xfer_done); } - if (status) - dev_err(&dspi->pdev->dev, - "Waiting for transfer to complete failed!\n");
if (transfer->delay_usecs) udelay(transfer->delay_usecs); @@ -1122,7 +1115,7 @@ static int dspi_probe(struct platform_device *pdev) goto out_clk_put; }
- init_waitqueue_head(&dspi->waitq); + init_completion(&dspi->xfer_done);
poll_mode: if (dspi->devtype_data->trans_mode == DSPI_DMA_MODE) {