LinuxKPI: add system_percpu_wq

In Linux v6.17 system_wq was replaced (renamed to) system_percpu_wq,
with the old name still present.

We just alias system_percpu_wq to linux_system_short_wq like we do
for system_wq to keep both around for the forseeable future.

Note: the original system_wq was a per-cpu queue upstream as well
based on my understanding but we never implemented it as such.
That means we are still lacking a per-cpu implementation for
system_percpu_wq but at least we do not change the status-quo
of the LinuxKPI implementation with this.

Note2: we should add a check somewhere for LINUXKPI_VESION >=
61700 to print a warning if anyone still uses the system_wq
to detect any possible sami-native or out-of-tree drivers
relying on this and not properly updating.

Sponsored by:	The FreeBSD Foundation
MFC after:	3 days
Reviewed by:	dumbbell; emaste (comments on previous review)
Differential Revision: https://reviews.freebsd.org/D57730

2 files changed, 10 insertions, 0 deletions

diff --git a/sys/compat/linuxkpi/common/include/linux/workqueue.h b/sys/compat/linuxkpi/common/include/linux/workqueue.h
index 66d3981d4229..b531d4f34658 100644
--- a/sys/compat/linuxkpi/common/include/linux/workqueue.h
+++ b/sys/compat/linuxkpi/common/include/linux/workqueue.h
@@ -237,6 +237,7 @@ extern struct workqueue_struct *system_long_wq;
 extern struct workqueue_struct *system_unbound_wq;
 extern struct workqueue_struct *system_highpri_wq;
 extern struct workqueue_struct *system_power_efficient_wq;
+extern struct workqueue_struct *system_percpu_wq;
 
 extern void linux_init_delayed_work(struct delayed_work *, work_func_t);
 extern void linux_work_fn(void *, int);
diff --git a/sys/compat/linuxkpi/common/src/linux_work.c b/sys/compat/linuxkpi/common/src/linux_work.c
index b1975d16025e..bb25893d9c71 100644
--- a/sys/compat/linuxkpi/common/src/linux_work.c
+++ b/sys/compat/linuxkpi/common/src/linux_work.c
@@ -57,6 +57,7 @@ struct workqueue_struct *system_long_wq;
 struct workqueue_struct *system_unbound_wq;
 struct workqueue_struct *system_highpri_wq;
 struct workqueue_struct *system_power_efficient_wq;
+struct workqueue_struct *system_percpu_wq;
 
 struct taskqueue *linux_irq_work_tq;
 
@@ -721,7 +722,14 @@ linux_work_init(void *arg)
 
 	/* populate the workqueue pointers */
 	system_long_wq = linux_system_long_wq;
+	/*
+	 * With Linux v6.17 system_wq was "renamed" to system_percpu_wq with the
+	 * old name staying around.
+	 * Note: neither implementation here does fully implement the per-cpu
+	 * characteristics upstream expects.
+	 */
 	system_wq = linux_system_short_wq;
+	system_percpu_wq = linux_system_short_wq;
 	system_power_efficient_wq = linux_system_short_wq;
 	system_unbound_wq = linux_system_short_wq;
 	system_highpri_wq = linux_system_short_wq;
@@ -737,6 +745,7 @@ linux_work_uninit(void *arg)
 	/* clear workqueue pointers */
 	system_long_wq = NULL;
 	system_wq = NULL;
+	system_percpu_wq = NULL;
 	system_power_efficient_wq = NULL;
 	system_unbound_wq = NULL;
 	system_highpri_wq = NULL;