[PATCH v2 08/12] lib/crc_kunit.c: add KUnit test suite for CRC library functions

[Guenter Roeck]

Hi,

On Sun, Dec 01, 2024 at 05:20:52PM -0800, Eric Biggers wrote:
> From: Eric Biggers <ebiggers at google.com>
> 
> Add a KUnit test suite for the crc16, crc_t10dif, crc32_le, crc32_be,
> crc32c, and crc64_be library functions.  It avoids code duplication by
> sharing most logic among all CRC variants.  The test suite includes:
> 
> - Differential fuzz test of each CRC function against a simple
>   bit-at-a-time reference implementation.
> - Test for CRC combination, when implemented by a CRC variant.
> - Optional benchmark of each CRC function with various data lengths.
> 
> This is intended as a replacement for crc32test and crc16_kunit, as well
> as a new test for CRC variants which didn't previously have a test.
> 
> Reviewed-by: Ard Biesheuvel <ardb at kernel.org>
> Reviewed-by: Martin K. Petersen <martin.petersen at oracle.com>
> Cc: Vinicius Peixoto <vpeixoto at lkcamp.dev>
> Signed-off-by: Eric Biggers <ebiggers at google.com>
> ---
...
> +
> +		nosimd = rand32() % 8 == 0;
> +
> +		/*
> +		 * Compute the CRC, and verify that it equals the CRC computed
> +		 * by a simple bit-at-a-time reference implementation.
> +		 */
> +		expected_crc = crc_ref(v, init_crc, &test_buffer[offset], len);
> +		if (nosimd)
> +			local_irq_disable();
> +		actual_crc = v->func(init_crc, &test_buffer[offset], len);
> +		if (nosimd)
> +			local_irq_enable();

This triggers a traceback on some arm systems.

[    7.810000]     ok 2 crc16_benchmark # SKIP not enabled
[    7.810000] ------------[ cut here ]------------
[    7.810000] WARNING: CPU: 0 PID: 1145 at kernel/softirq.c:369 __local_bh_enable_ip+0x118/0x194
[    7.810000] Modules linked in:
[    7.810000] CPU: 0 UID: 0 PID: 1145 Comm: kunit_try_catch Tainted: G                 N 6.14.0-rc7-00196-g88d324e69ea9 #1
[    7.810000] Tainted: [N]=TEST
[    7.810000] Hardware name: NPCM7XX Chip family
[    7.810000] Call trace:
[    7.810000]  unwind_backtrace from show_stack+0x10/0x14
[    7.810000]  show_stack from dump_stack_lvl+0x7c/0xac
[    7.810000]  dump_stack_lvl from __warn+0x7c/0x1b8
[    7.810000]  __warn from warn_slowpath_fmt+0x19c/0x1a4
[    7.810000]  warn_slowpath_fmt from __local_bh_enable_ip+0x118/0x194
[    7.810000]  __local_bh_enable_ip from crc_t10dif_arch+0xd4/0xe8
[    7.810000]  crc_t10dif_arch from crc_t10dif_wrapper+0x14/0x1c
[    7.810000]  crc_t10dif_wrapper from crc_main_test+0x178/0x360
[    7.810000]  crc_main_test from kunit_try_run_case+0x78/0x1e0
[    7.810000]  kunit_try_run_case from kunit_generic_run_threadfn_adapter+0x1c/0x34
[    7.810000]  kunit_generic_run_threadfn_adapter from kthread+0x118/0x254
[    7.810000]  kthread from ret_from_fork+0x14/0x28
[    7.810000] Exception stack(0xe3651fb0 to 0xe3651ff8)
[    7.810000] 1fa0:                                     00000000 00000000 00000000 00000000
[    7.810000] 1fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
[    7.810000] 1fe0: 00000000 00000000 00000000 00000000 00000013 00000000
[    7.810000] irq event stamp: 29
[    7.810000] hardirqs last  enabled at (27): [<c037875c>] __local_bh_enable_ip+0xb4/0x194
[    7.810000] hardirqs last disabled at (28): [<c0b09684>] crc_main_test+0x2e4/0x360
[    7.810000] softirqs last  enabled at (26): [<c032a3ac>] kernel_neon_end+0x0/0x1c
[    7.810000] softirqs last disabled at (29): [<c032a3c8>] kernel_neon_begin+0x0/0x70
[    7.810000] ---[ end trace 0000000000000000 ]---
[    8.050000]     # crc_t10dif_test: pass:1 fail:0 skip:0 total:1

kernel_neon_end() calls local_bh_enable() which apparently conflicts with
the local_irq_disable() in above code.

Guenter