> Cc: my personal email qiang.zhang1211@xxxxxxxxx
>
> > When unloading rcutorture kmod will trigger the following callstack:
> >
> > insmod rcutorture.ko
> > rmmod rcutorture.ko
> >
> > [ 209.437327] WARNING: CPU: 0 PID: 508 at kernel/workqueue.c:3167 __flush_work+0x50a/0x540
> > [ 209.437346] Modules linked in: rcutorture(-) torture [last unloaded: rcutorture]
> > [ 209.437382] CPU: 0 PID: 508 Comm: rmmod Tainted: G W 6.3.0-rc1-yocto-standard+
> > [ 209.437406] RIP: 0010:__flush_work+0x50a/0x540
> > .....
> > [ 209.437758] flush_delayed_work+0x36/0x90
> > [ 209.437776] cleanup_srcu_struct+0x68/0x2e0
> > [ 209.437817] srcu_module_notify+0x71/0x140
> > [ 209.437854] blocking_notifier_call_chain+0x9d/0xd0
> > [ 209.437880] __x64_sys_delete_module+0x223/0x2e0
> > [ 209.438046] do_syscall_64+0x43/0x90
> > [ 209.438062] entry_SYSCALL_64_after_hwframe+0x72/0xdc
> >
> > flush_delayed_work()
> > ->__flush_work()
> > ->if (WARN_ON(!work->func))
> > return false;
> >
> > For srcu objects defined with DEFINE_SRCU() or DEFINE_STATIC_SRCU(),
> > when compiling and loading as modules, the srcu_module_coming() is
> > invoked, allocate memory for srcu structure's->sda and initialize
> > sda structure, due to not fully initialize srcu structure's->sup,
> > so at this time the sup structure's->work.work.func is null, if not
> > invoke init_srcu_struct_fields() before unloading modules, the
> > __flush_work() be invoked in srcu_module_going() and find work->func
> > is empty, will raise the warning above.
> >
> > This commit add the check of srcu_sup structure's->srcu_gp_seq_needed
> > to determine whether the check_init_srcu_struct() has been invoked to
> > initialize srcu objects in srcu_module_going(), if not initialize, there
> > are no pending or running works, so there is no need to flush, only invoke
> > free_percpu() to release srcu structure's->sda.
> >
> > Co-developed-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
> >
> >Thank you for the testing, bug-finding, and problem-solving!
> >
> >In theory, you would need a Signed-off-by here from me as well, but
> >in practice bisectability means that this must be folded into this:
> >
> >e7c778489040 ("srcu: Use static init for statically allocated in-module srcu_struct")
> >
> >This will of course be with attribution.
> >
> > Signed-off-by: Zqiang <qiang1.zhang@xxxxxxxxx>
> >
> >But this is still a bit more complex than needed. How about something
> >like this?
>
> Agree, from a logical point of view, this is more rigorous😊.
>
>And I finally got around to doing some modprobe/rmmod testing myself,
>and it passes eleven cycles.
>
>May I add your Tested-by to the series?
Of course I am glad to.
Thanks
Zqiang
>
> Thanx, Paul
>
> Thanks
> Zqiang
>
> >
> > Thanx, Paul
> >
> >------------------------------------------------------------------------
> >
> >/* Initialize any global-scope srcu_struct structures used by this module. */
> >static int srcu_module_coming(struct module *mod)
> >{
> > int i;
> > struct srcu_struct *ssp;
> > struct srcu_struct **sspp = mod->srcu_struct_ptrs;
> >
> > for (i = 0; i < mod->num_srcu_structs; i++) {
> > ssp = *(sspp++);
> > ssp->sda = alloc_percpu(struct srcu_data);
> > if (WARN_ON_ONCE(!ssp->sda))
> > return -ENOMEM;
> > }
> > return 0;
> >}
> >
> >/* Clean up any global-scope srcu_struct structures used by this module. */
> >static void srcu_module_going(struct module *mod)
> >{
> > int i;
> > struct srcu_struct *ssp;
> > struct srcu_struct **sspp = mod->srcu_struct_ptrs;
> >
> > for (i = 0; i < mod->num_srcu_structs; i++) {
> > ssp = *(sspp++);
> > if (!rcu_seq_state(smp_load_acquire(&ssp->srcu_sup->srcu_gp_seq_needed)) &&
> > !WARN_ON_ONCE(!ssp->srcu_sup->sda_is_static))
> > cleanup_srcu_struct(ssp);
> > free_percpu(ssp->sda);
> > }
> >}
