refactor all tasklet users into other APIs

[kees]

During the work to modernize the tasklet API, there was a request to just entirely remove it. This is much more work than just making the API safer, so it is considered the "next step" in dealing with tasklets. In the meantime, comments were added to suggest people quit using tasklets in new code. ;)

https://lore.kernel.org/driverdev-devel/20200716081538.2sivhkj4hcyrusem@linutronix.de/

Example conversions from tasklet into:

• threaded irq
  • commit ce4f257
  • commit 2ac55da
• softirq hrtimer
  • commit ecb9f80
  • commit b03bbbe
• work queue
  • commit 2b3d298
  • commit 8653d71
  • commit fe10171

[allenpais]

@kees Can I get this issue assigned to me. I am in the process of rebasing the changes and will send a few out subsystem wise.

[kees]

Sure! I can't figure out why folks can't do self-assignment in this tracker. Hmmm

[kees]

Hi! Any progress on doing this refactoring? What do some conversion examples look like?

[allenpais]

@kees I have most of it ready, couple of subsystems and they should be ready for review.

Also, since we are completely removing tasklets and moving to either workqueue or threaded interrupts(in some cases),
The code now heavily uses container_of macro.

Eg:

•   struct nitrox_q_vector *qvec = (void *)(uintptr_t)(data);
  

•   struct nitrox_q_vector *qvec = 
  

•           container_of(work, struct nitrox_q_vector, resp_work);
  

Instead, I was thinking of having a function like from_wq() similar to from_tasklet() which would
be cleaner implementation.

#define from_wq(var, callback_wq, wq_fieldname)
container_of(callback_wq, typeof(*var), wq_fieldname)

[kees]

Yay! That's excellent. Do you have a tree we can link to from this issue?

And since it seems Linus was not excited about the container_of wrapper helpers, so I think it's best to leave them open-coded. I think it looks nicer with a helper, but if it makes it easier to merge, then I guess open-coded is the way to go. :)

[allenpais]

Sure, I will rebase all the changes and push it out.

Thanks. I will drop the wrapper.

[allenpais]

I have pushed a branch which will contain the series(cleanup):
https://github.com/allenpais/refactor_takslets.git

Will have other sub-systems pushed in a couple of days.

[kees]

I have pushed a branch which will contain the series(cleanup): https://github.com/allenpais/refactor_takslets.git

Will have other sub-systems pushed in a couple of days.

Nice! Did you do this with coccinelle or manually? Maybe send this one as-is to get any feedback that might be useful for the other subsystems?

[allenpais]

@kees It was manual as not all drivers are converted to use workqueues. Some are using threaded_irq.

I have send out the first series for review:
https://lkml.org/lkml/2022/4/19/1411

Networking has the biggest set of changes, which I have split into small sets which makes it easier for the maintainer to review/merge. Changes on the rest of the sub-systems are fairly small and could be carried as a single patch(hopefully).

[kees]

Attention has returned to tasklets!
https://lwn.net/Articles/960041/

[allenpais]

Attention has returned to tasklets! https://lwn.net/Articles/960041/

Thank Kees. Yes, I have been working with Tejun and have the series tested. The next steps are planned and am working on getting the RFC ready.

[kees]

Conversions ongoing:
https://lore.kernel.org/lkml/CAOMdWSLF9AaQF0ux03-tonw-Jy+4rXdKEZGzPrp_v+fnas6SnQ@mail.gmail.com/

[allenpais]

Status of conversions(02/21/2024):

https://github.com/allenpais/for-6.9-bh-conversions

0001-dma-Convert-from-tasklet-to-BH-workqueue.patch
0002-IB-Convert-from-tasklet-to-BH-workqueue.patch
0003-USB-Convert-from-tasklet-to-BH-workqueue.patch
0004-mailbox-Convert-from-tasklet-to-BH-workqueue.patch
0005-ipmi-Convert-from-tasklet-to-BH-workqueue.patch
0006-s390-Convert-from-tasklet-to-BH-workqueue.patch
0007-drivers-media-Convert-from-tasklet-to-BH-workqueue.patch
0008-mmc-Convert-from-tasklet-to-BH-workqueue.patch

[allenpais]

Status of Conversions(03/11/2024):

I have a series ready for review(a set of 10 patches):
https://github.com/allenpais/for-6.9-bh-conversions/tree/for-6.9

0001-kernel-Introduce-enable_and_queue_work-convenience-f.patch | 64 ++
0002-dma-Convert-from-tasklet-to-BH-workqueue.patch | 1991 ++++++++++++++++++++++++++++++++++--------------------------
0003-IB-Convert-from-tasklet-to-BH-workqueue.patch | 480 ++++++++-------
0004-USB-Convert-from-tasklet-to-BH-workqueue.patch | 356 +++++++----
0005-mailbox-Convert-from-tasklet-to-BH-workqueue.patch | 68 ++-
0006-ipmi-Convert-from-tasklet-to-BH-workqueue.patch | 54 +-
0007-s390-Convert-from-tasklet-to-BH-workqueue.patch | 279 +++++----
0008-drivers-media-Convert-from-tasklet-to-BH-workqueue.patch | 673 ++++++++++++--------
0009-mmc-Convert-from-tasklet-to-BH-workqueue.patch | 491 +++++++++------
0010-hyperv-Convert-from-tasklet-to-BH-workqueue.patch | 392 ++++++++++++

A series that still needs some work(testing and cleanup):
https:/github.com/allenpais/for-6.9-bh-conversions/tree/for-6.9-wip (This
series contains changes to all the files that use tasklets in drivers/*)
0001-dma-Convert-from-tasklet-to-BH-workqueue.patch | 3381 -------------------------------------------------------------------------------------------------
0001-memstick-Convert-from-tasklet-to-BH-workqueue.patch | 150 +++++
0002-IB-Convert-from-tasklet-to-BH-workqueue.patch | 864 -------------------------
0002-tty-Convert-from-tasklet-to-BH-workqueue.patch | 513 +++++++++++++++
0003-USB-Convert-from-tasklet-to-BH-workqueue.patch | 594 ------------------
0003-scsi-Convert-from-tasklet-to-BH-workqueue.patch | 819 ++++++++++++++++++++++++
0004-mailbox-Convert-from-tasklet-to-BH-workqueue.patch | 158 -----
0004-wireless-Convert-from-tasklet-to-BH-workqueue.patch | 4014 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
0005-ethernet-Convert-from-tasklet-to-BH-workqueue.patch | 3554 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
0005-ipmi-Convert-from-tasklet-to-BH-workqueue.patch | 134 ----
0006-archnet-Convert-from-tasklet-to-BH-workqueue.patch | 99 +++
0006-s390-Convert-from-tasklet-to-BH-workqueue.patch | 842 -------------------------
0007-drivers-media-Convert-from-tasklet-to-BH-workqueue.patch | 1132 ---------------------------------
0007-wwan-Convert-from-tasklet-to-BH-workqueue.patch | 206 ++++++
0008-mmc-Convert-from-tasklet-to-BH-workqueue.patch | 1178 ----------------------------------
0008-net-Convert-from-tasklet-to-BH-workqueue.patch | 1046 ++++++++++++++++++++++++++++++
0009-rapidio-Convert-from-tasklet-to-BH-workqueue.patch | 62 ++
0010-pci-hyperv-Convert-from-tasklet-to-BH-workqueue.patch | 77 +++
0011-input-Convert-from-tasklet-to-BH-workqueue.patch | 105 ++++
0012-md-Convert-from-tasklet-to-BH-workqueue.patch | 138 ++++
0013-firewire-Convert-from-tasklet-to-BH-workqueue.patch | 224 +++++++
0014-misc-Convert-from-tasklet-to-BH-workqueue.patch | 88 +++
0015-hsi-Convert-from-tasklet-to-BH-workqueue.patch | 139 ++++
0016-bus-Convert-from-tasklet-to-BH-workqueue.patch | 62 ++
0017-crypto-Convert-from-tasklet-to-BH-workqueue.patch | 1820 +++++++++++++++++++++++++++++++++++++++++++++++++++++
0018-net-Convert-from-tasklet-to-BH-workqueue.patch | 933 +++++++++++++++++++++++++++
27 files changed, 14382 insertions(+), 8283 deletions(-)