[PATCH] [RFC] scsi: Convert from tasklet to BH workqueue

[Allen Pais]

> On May 2, 2024, at 7:03 PM, Michael Ellerman <mpe at ellerman.id.au> wrote:
> 
> Allen Pais <apais at linux.microsoft.com> writes:
>> The only generic interface to execute asynchronously in the BH context is
>> tasklet; however, it's marked deprecated and has some design flaws. To
>> replace tasklets, BH workqueue support was recently added. A BH workqueue
>> behaves similarly to regular workqueues except that the queued work items
>> are executed in the BH context.
>> 
>> This patch converts drivers/scsi/* from tasklet to BH workqueue.
>> 
>> Based on the work done by Tejun Heo <tj at kernel.org>
>> Branch: https://git.kernel.org/pub/scm/linux/kernel/git/tj/wq.git for-6.10
>> 
>> Signed-off-by: Allen Pais <allen.lkml at gmail.com>
>> ---
>> drivers/scsi/aic7xxx/aic7xxx_osm.c          |  2 +-
>> drivers/scsi/aic94xx/aic94xx_hwi.c          | 14 ++--
>> drivers/scsi/aic94xx/aic94xx_hwi.h          |  5 +-
>> drivers/scsi/aic94xx/aic94xx_scb.c          | 36 +++++-----
>> drivers/scsi/aic94xx/aic94xx_task.c         | 14 ++--
>> drivers/scsi/aic94xx/aic94xx_tmf.c          | 34 ++++-----
>> drivers/scsi/esas2r/esas2r.h                | 12 ++--
>> drivers/scsi/esas2r/esas2r_init.c           | 14 ++--
>> drivers/scsi/esas2r/esas2r_int.c            | 18 ++---
>> drivers/scsi/esas2r/esas2r_io.c             |  2 +-
>> drivers/scsi/esas2r/esas2r_main.c           | 16 ++---
>> drivers/scsi/ibmvscsi/ibmvfc.c              | 16 ++---
>> drivers/scsi/ibmvscsi/ibmvfc.h              |  3 +-
>> drivers/scsi/ibmvscsi/ibmvscsi.c            | 16 ++---
>> drivers/scsi/ibmvscsi/ibmvscsi.h            |  3 +-
>> drivers/scsi/ibmvscsi_tgt/ibmvscsi_tgt.c    | 15 ++--
>> drivers/scsi/ibmvscsi_tgt/ibmvscsi_tgt.h    |  3 +-
> 
> Something there is giving me a build failure (ppc64le_guest_defconfig):
> 
>  + make -s 'CC=ccache powerpc64le-linux-gnu-gcc' -j 4
>  /linux/drivers/scsi/ibmvscsi/ibmvscsi.c: In function 'ibmvscsi_init_crq_queue':
>  Error: /linux/drivers/scsi/ibmvscsi/ibmvscsi.c:370:331: error: 'ibmvscsi_work' undeclared (first use in this function)
>  /linux/drivers/scsi/ibmvscsi/ibmvscsi.c:370:331: note: each undeclared identifier is reported only once for each function it appears in
>  /linux/scripts/Makefile.build:244: recipe for target 'drivers/scsi/ibmvscsi/ibmvscsi.o' failed
>  /linux/scripts/Makefile.build:485: recipe for target 'drivers/scsi/ibmvscsi' failed
>  /linux/scripts/Makefile.build:485: recipe for target 'drivers/scsi' failed
>  /linux/scripts/Makefile.build:485: recipe for target 'drivers' failed
>  /linux/drivers/scsi/ibmvscsi/ibmvscsi.c: In function 'ibmvscsi_probe':
>  Error: /linux/drivers/scsi/ibmvscsi/ibmvscsi.c:2255:78: error: passing argument 1 of 'kthread_create_on_node' from incompatible pointer type [-Werror=incompatible-pointer-types]
>  In file included from /linux/drivers/scsi/ibmvscsi/ibmvscsi.c:56:0:
>  /linux/include/linux/kthread.h:11:21: note: expected 'int (*)(void *)' but argument is of type 'int (*)(struct work_struct *)'
>   struct task_struct *kthread_create_on_node(int (*threadfn)(void *data),
>                       ^
>  /linux/drivers/scsi/ibmvscsi/ibmvscsi.c: At top level:
>  Warning: /linux/drivers/scsi/ibmvscsi/ibmvscsi.c:212:13: warning: 'ibmvscsi_task' defined but not used [-Wunused-function]
>   static void ibmvscsi_task(void *data)
>               ^
>  Warning: cc1: warning: unrecognized command line option '-Wno-shift-negative-value'
>  Warning: cc1: warning: unrecognized command line option '-Wno-stringop-overflow'
>  cc1: some warnings being treated as errors
>  make[6]: *** [drivers/scsi/ibmvscsi/ibmvscsi.o] Error 1
>  make[5]: *** [drivers/scsi/ibmvscsi] Error 2
>  make[4]: *** [drivers/scsi] Error 2
>  make[3]: *** [drivers] Error 2
>  make[3]: *** Waiting for unfinished jobs....
> 
> Full log here: https://github.com/linuxppc/linux-snowpatch/actions/runs/8930174372/job/24529645923

 Thank you for testing it out. Unfortunately, I did not cross-compile it.
Will fix this in v2.

- Allen

> 
> Cross compile instructions if you're keen: https://github.com/linuxppc/wiki/wiki/Building-powerpc-kernels
> 
> cheers