linux-kernel - Re: [PATCH 3/7] xen/events: reduce externally visible helper functions

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Date:   Mon, 13 Nov 2023 15:53:28 +0000
From:   Oleksandr Tyshchenko <Oleksandr_Tyshchenko@...m.com>
To:     Juergen Gross <jgross@...e.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     Stefano Stabellini <sstabellini@...nel.org>,
        "xen-devel@...ts.xenproject.org" <xen-devel@...ts.xenproject.org>
Subject: Re: [PATCH 3/7] xen/events: reduce externally visible helper
 functions



On 16.10.23 09:28, Juergen Gross wrote:


Hello Juergen

> get_evtchn_to_irq() has only one external user while irq_from_evtchn()
> provides the same functionality and is exported for a wider user base.
> Modify the only external user of get_evtchn_to_irq() to use
> irq_from_evtchn() instead and make get_evtchn_to_irq() static.
> 
> evtchn_from_irq() and irq_from_virq() have a single external user and
> can easily be combined to a new helper irq_evtchn_from_virq() allowing
> to drop irq_from_virq() and to make evtchn_from_irq() static.
> 
> Signed-off-by: Juergen Gross <jgross@...e.com>


Reviewed-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@...m.com>

Two NITs *NOT* directly related to current patch below.


> ---
>   drivers/xen/events/events_2l.c       |  8 ++++----
>   drivers/xen/events/events_base.c     | 13 +++++++++----
>   drivers/xen/events/events_internal.h |  1 -
>   include/xen/events.h                 |  4 ++--
>   4 files changed, 15 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/xen/events/events_2l.c b/drivers/xen/events/events_2l.c
> index b8f2f971c2f0..e3585330cf98 100644
> --- a/drivers/xen/events/events_2l.c
> +++ b/drivers/xen/events/events_2l.c
> @@ -171,11 +171,11 @@ static void evtchn_2l_handle_events(unsigned cpu, struct evtchn_loop_ctrl *ctrl)
>   	int i;
>   	struct shared_info *s = HYPERVISOR_shared_info;
>   	struct vcpu_info *vcpu_info = __this_cpu_read(xen_vcpu);
> +	evtchn_port_t evtchn;
>   
>   	/* Timer interrupt has highest priority. */
> -	irq = irq_from_virq(cpu, VIRQ_TIMER);
> +	irq = irq_evtchn_from_virq(cpu, VIRQ_TIMER, &evtchn);
>   	if (irq != -1) {
> -		evtchn_port_t evtchn = evtchn_from_irq(irq);

Most users of evtchn_from_irq() check returned evtchn via VALID_EVTCHN() 
as it might be 0. But this user doesn't.


>   		word_idx = evtchn / BITS_PER_LONG;
>   		bit_idx = evtchn % BITS_PER_LONG;
>   		if (active_evtchns(cpu, s, word_idx) & (1ULL << bit_idx))
> @@ -328,9 +328,9 @@ irqreturn_t xen_debug_interrupt(int irq, void *dev_id)
>   	for (i = 0; i < EVTCHN_2L_NR_CHANNELS; i++) {
>   		if (sync_test_bit(i, BM(sh->evtchn_pending))) {
>   			int word_idx = i / BITS_PER_EVTCHN_WORD;
> -			printk("  %d: event %d -> irq %d%s%s%s\n",
> +			printk("  %d: event %d -> irq %u%s%s%s\n",

checkpatch.pl says:

WARNING: printk() should include KERN_<LEVEL> facility level
#37: FILE: drivers/xen/events/events_2l.c:331:
+			printk("  %d: event %d -> irq %u%s%s%s\n",


>   			       cpu_from_evtchn(i), i,
> -			       get_evtchn_to_irq(i),
> +			       irq_from_evtchn(i),
>   			       sync_test_bit(word_idx, BM(&v->evtchn_pending_sel))
>   			       ? "" : " l2-clear",
>   			       !sync_test_bit(i, BM(sh->evtchn_mask))
> 

[snip]