@@ -272,7 +272,7 @@ The available attributes are:
echo async_irq > /sys/bus/dsa/drivers/crypto/sync_mode
Async mode without interrupts (caller must poll) can be enabled by
- writing 'async' to it::
+ writing 'async' to it (please see Caveat)::
echo async > /sys/bus/dsa/drivers/crypto/sync_mode
@@ -283,6 +283,13 @@ The available attributes are:
The default mode is 'sync'.
+ Caveat: since the only mechanism that iaa_crypto currently implements
+ for async polling without interrupts is via the 'sync' mode as
+ described earlier, writing 'async' to
+ '/sys/bus/dsa/drivers/crypto/sync_mode' will internally enable the
+ 'sync' mode. This is to ensure correct iaa_crypto behavior until true
+ async polling without interrupts is enabled in iaa_crypto.
+
.. _iaa_default_config:
IAA Default Configuration
@@ -173,7 +173,7 @@ static int set_iaa_sync_mode(const char *name)
async_mode = false;
use_irq = false;
} else if (sysfs_streq(name, "async")) {
- async_mode = true;
+ async_mode = false;
use_irq = false;
} else if (sysfs_streq(name, "async_irq")) {
async_mode = true;
With the latest mm-unstable, setting the iaa_crypto sync_mode to 'async' causes crypto testmgr.c test_acomp() failure and dmesg call traces, and zswap being unable to use 'deflate-iaa' as a compressor: echo async > /sys/bus/dsa/drivers/crypto/sync_mode [ 255.271030] zswap: compressor deflate-iaa not available [ 369.960673] INFO: task cryptomgr_test:4889 blocked for more than 122 seconds. [ 369.970127] Not tainted 6.13.0-rc1-mm-unstable-12-16-2024+ #324 [ 369.977411] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 369.986246] task:cryptomgr_test state:D stack:0 pid:4889 tgid:4889 ppid:2 flags:0x00004000 [ 369.986253] Call Trace: [ 369.986256] <TASK> [ 369.986260] __schedule+0x45c/0xfa0 [ 369.986273] schedule+0x2e/0xb0 [ 369.986277] schedule_timeout+0xe7/0x100 [ 369.986284] ? __prepare_to_swait+0x4e/0x70 [ 369.986290] wait_for_completion+0x8d/0x120 [ 369.986293] test_acomp+0x284/0x670 [ 369.986305] ? __pfx_cryptomgr_test+0x10/0x10 [ 369.986312] alg_test_comp+0x263/0x440 [ 369.986315] ? sched_balance_newidle+0x259/0x430 [ 369.986320] ? __pfx_cryptomgr_test+0x10/0x10 [ 369.986323] alg_test.part.27+0x103/0x410 [ 369.986326] ? __schedule+0x464/0xfa0 [ 369.986330] ? __pfx_cryptomgr_test+0x10/0x10 [ 369.986333] cryptomgr_test+0x20/0x40 [ 369.986336] kthread+0xda/0x110 [ 369.986344] ? __pfx_kthread+0x10/0x10 [ 369.986346] ret_from_fork+0x2d/0x40 [ 369.986355] ? __pfx_kthread+0x10/0x10 [ 369.986358] ret_from_fork_asm+0x1a/0x30 [ 369.986365] </TASK> This happens because the only async polling without interrupts that iaa_crypto currently implements is with the 'sync' mode. With 'async', iaa_crypto calls to compress/decompress submit the descriptor and return -EINPROGRESS, without any mechanism in the driver to poll for completions. Hence callers such as test_acomp() in crypto/testmgr.c or zswap, that wrap the calls to crypto_acomp_compress() and crypto_acomp_decompress() in synchronous wrappers, will block indefinitely. Even before zswap can notice this problem, the crypto testmgr.c's test_acomp() will fail and prevent registration of "deflate-iaa" as a valid crypto acomp algorithm, thereby disallowing the use of "deflate-iaa" as a zswap compress (zswap will fall-back to the default compressor in this case). To fix this issue, this patch modifies the iaa_crypto sync_mode set function to treat 'async' equivalent to 'sync', so that the correct and only supported driver async polling without interrupts implementation is enabled, and zswap can use 'deflate-iaa' as the compressor. Hence, with this patch, this is what will happen: echo async > /sys/bus/dsa/drivers/crypto/sync_mode cat /sys/bus/dsa/drivers/crypto/sync_mode sync There are no crypto/testmgr.c test_acomp() errors, no call traces and zswap can use 'deflate-iaa' without any errors. The iaa_crypto documentation has also been updated to mention this caveat with 'async' and what to expect with this fix. True iaa_crypto async polling without interrupts is enabled in patch "crypto: iaa - Implement batch_compress(), batch_decompress() API in iaa_crypto." [1] which is under review as part of the "zswap IAA compress batching" patch-series [2]. Until this is merged, we would appreciate it if this current patch can be considered for a hotfix. [1]: https://patchwork.kernel.org/project/linux-mm/patch/20241221063119.29140-5-kanchana.p.sridhar@intel.com/ [2]: https://patchwork.kernel.org/project/linux-mm/list/?series=920084 Fixes: 09646c98d ("crypto: iaa - Add irq support for the crypto async interface") Signed-off-by: Kanchana P Sridhar <kanchana.p.sridhar@intel.com> --- Documentation/driver-api/crypto/iaa/iaa-crypto.rst | 9 ++++++++- drivers/crypto/intel/iaa/iaa_crypto_main.c | 2 +- 2 files changed, 9 insertions(+), 2 deletions(-) base-commit: 13d127a82b5c70061560c65fb083e30e79363874