mainlining shenanigans
4f5ee75ea1
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:
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| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
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| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
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| .clang-format | ||
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| COPYING | ||
| CREDITS | ||
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| Makefile | ||
| README | ||
Linux kernel
============
There are several guides for kernel developers and users. These guides can
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Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
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There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.