On Wed, Mar 27, 2024 at 04:03:11PM +0000, Allen Pais wrote:
> 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/infiniband/* from tasklet to BH workqueue.

I think you mean drivers/char/ipmi/* here.

I believe that work queues items are execute single-threaded for a work
queue, so this should be good.  I need to test this, though.  It may be
that an IPMI device can have its own work queue; it may not be important
to run it in bh context.

-corey

> 
> Based on the work done by Tejun Heo <t...@kernel.org>
> Branch: https://git.kernel.org/pub/scm/linux/kernel/git/tj/wq.git for-6.10
> 
> Signed-off-by: Allen Pais <allen.l...@gmail.com>
> ---
>  drivers/char/ipmi/ipmi_msghandler.c | 30 ++++++++++++++---------------
>  1 file changed, 15 insertions(+), 15 deletions(-)
> 
> diff --git a/drivers/char/ipmi/ipmi_msghandler.c 
> b/drivers/char/ipmi/ipmi_msghandler.c
> index b0eedc4595b3..fce2a2dbdc82 100644
> --- a/drivers/char/ipmi/ipmi_msghandler.c
> +++ b/drivers/char/ipmi/ipmi_msghandler.c
> @@ -36,12 +36,13 @@
>  #include <linux/nospec.h>
>  #include <linux/vmalloc.h>
>  #include <linux/delay.h>
> +#include <linux/workqueue.h>
>  
>  #define IPMI_DRIVER_VERSION "39.2"
>  
>  static struct ipmi_recv_msg *ipmi_alloc_recv_msg(void);
>  static int ipmi_init_msghandler(void);
> -static void smi_recv_tasklet(struct tasklet_struct *t);
> +static void smi_recv_work(struct work_struct *t);
>  static void handle_new_recv_msgs(struct ipmi_smi *intf);
>  static void need_waiter(struct ipmi_smi *intf);
>  static int handle_one_recv_msg(struct ipmi_smi *intf,
> @@ -498,13 +499,13 @@ struct ipmi_smi {
>       /*
>        * Messages queued for delivery.  If delivery fails (out of memory
>        * for instance), They will stay in here to be processed later in a
> -      * periodic timer interrupt.  The tasklet is for handling received
> +      * periodic timer interrupt.  The work is for handling received
>        * messages directly from the handler.
>        */
>       spinlock_t       waiting_rcv_msgs_lock;
>       struct list_head waiting_rcv_msgs;
>       atomic_t         watchdog_pretimeouts_to_deliver;
> -     struct tasklet_struct recv_tasklet;
> +     struct work_struct recv_work;
>  
>       spinlock_t             xmit_msgs_lock;
>       struct list_head       xmit_msgs;
> @@ -704,7 +705,7 @@ static void clean_up_interface_data(struct ipmi_smi *intf)
>       struct cmd_rcvr  *rcvr, *rcvr2;
>       struct list_head list;
>  
> -     tasklet_kill(&intf->recv_tasklet);
> +     cancel_work_sync(&intf->recv_work);
>  
>       free_smi_msg_list(&intf->waiting_rcv_msgs);
>       free_recv_msg_list(&intf->waiting_events);
> @@ -1319,7 +1320,7 @@ static void free_user(struct kref *ref)
>  {
>       struct ipmi_user *user = container_of(ref, struct ipmi_user, refcount);
>  
> -     /* SRCU cleanup must happen in task context. */
> +     /* SRCU cleanup must happen in work context. */
>       queue_work(remove_work_wq, &user->remove_work);
>  }
>  
> @@ -3605,8 +3606,7 @@ int ipmi_add_smi(struct module         *owner,
>       intf->curr_seq = 0;
>       spin_lock_init(&intf->waiting_rcv_msgs_lock);
>       INIT_LIST_HEAD(&intf->waiting_rcv_msgs);
> -     tasklet_setup(&intf->recv_tasklet,
> -                  smi_recv_tasklet);
> +     INIT_WORK(&intf->recv_work, smi_recv_work);
>       atomic_set(&intf->watchdog_pretimeouts_to_deliver, 0);
>       spin_lock_init(&intf->xmit_msgs_lock);
>       INIT_LIST_HEAD(&intf->xmit_msgs);
> @@ -4779,7 +4779,7 @@ static void handle_new_recv_msgs(struct ipmi_smi *intf)
>                        * To preserve message order, quit if we
>                        * can't handle a message.  Add the message
>                        * back at the head, this is safe because this
> -                      * tasklet is the only thing that pulls the
> +                      * work is the only thing that pulls the
>                        * messages.
>                        */
>                       list_add(&smi_msg->link, &intf->waiting_rcv_msgs);
> @@ -4812,10 +4812,10 @@ static void handle_new_recv_msgs(struct ipmi_smi 
> *intf)
>       }
>  }
>  
> -static void smi_recv_tasklet(struct tasklet_struct *t)
> +static void smi_recv_work(struct work_struct *t)
>  {
>       unsigned long flags = 0; /* keep us warning-free. */
> -     struct ipmi_smi *intf = from_tasklet(intf, t, recv_tasklet);
> +     struct ipmi_smi *intf = from_work(intf, t, recv_work);
>       int run_to_completion = intf->run_to_completion;
>       struct ipmi_smi_msg *newmsg = NULL;
>  
> @@ -4866,7 +4866,7 @@ void ipmi_smi_msg_received(struct ipmi_smi *intf,
>  
>       /*
>        * To preserve message order, we keep a queue and deliver from
> -      * a tasklet.
> +      * a work.
>        */
>       if (!run_to_completion)
>               spin_lock_irqsave(&intf->waiting_rcv_msgs_lock, flags);
> @@ -4887,9 +4887,9 @@ void ipmi_smi_msg_received(struct ipmi_smi *intf,
>               spin_unlock_irqrestore(&intf->xmit_msgs_lock, flags);
>  
>       if (run_to_completion)
> -             smi_recv_tasklet(&intf->recv_tasklet);
> +             smi_recv_work(&intf->recv_work);
>       else
> -             tasklet_schedule(&intf->recv_tasklet);
> +             queue_work(system_bh_wq, &intf->recv_work);
>  }
>  EXPORT_SYMBOL(ipmi_smi_msg_received);
>  
> @@ -4899,7 +4899,7 @@ void ipmi_smi_watchdog_pretimeout(struct ipmi_smi *intf)
>               return;
>  
>       atomic_set(&intf->watchdog_pretimeouts_to_deliver, 1);
> -     tasklet_schedule(&intf->recv_tasklet);
> +     queue_work(system_bh_wq, &intf->recv_work);
>  }
>  EXPORT_SYMBOL(ipmi_smi_watchdog_pretimeout);
>  
> @@ -5068,7 +5068,7 @@ static bool ipmi_timeout_handler(struct ipmi_smi *intf,
>                                      flags);
>       }
>  
> -     tasklet_schedule(&intf->recv_tasklet);
> +     queue_work(system_bh_wq, &intf->recv_work);
>  
>       return need_timer;
>  }
> -- 
> 2.17.1
> 
> 

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