Re: [PATCH linux-next] genirq: use sysfs_emit() instead of scnprintf().

[Jiri Slaby]

On 17. 03. 25, 7:07, Jiri Slaby wrote:
> Hi,
>
> your e-mail is both multipart and base64 encoded :(. Pls fix up your 
> setup first.
>
> On 15. 03. 25, 7:17, xie.ludan@xxxxxxxxxx wrote:
> > From: XieLudan <xie.ludan@xxxxxxxxxx>
> >
> >
> > Follow the advice in Documentation/filesystems/sysfs.rst:
> >
> > show() should only use sysfs_emit() or sysfs_emit_at() when formatting
> >
> > the value to be returned to user space.
> >
> >
> > Signed-off-by: XieLudan <xie.ludan@xxxxxxxxxx>
> >
> > ---
> >
> >   kernel/irq/irqdesc.c | 12 ++++++------
> >
> >   1 file changed, 6 insertions(+), 6 deletions(-)
> >
> >
> > diff --git a/kernel/irq/irqdesc.c b/kernel/irq/irqdesc.c
> >
> > index 287830739783..8ffe12fe5af6 100644
> >
> > --- a/kernel/irq/irqdesc.c
> >
> > +++ b/kernel/irq/irqdesc.c
> >
> > @@ -257,11 +257,11 @@ static ssize_t per_cpu_count_show(struct kobject 
> > *kobj,
> >
> > for_each_possible_cpu(cpu) {
> >
> > unsigned int c = irq_desc_kstat_cpu(desc, cpu);
> >
> > -ret += scnprintf(buf + ret, PAGE_SIZE - ret, "%s%u", p, c);
> >
> > +ret += sysfs_emit(buf + ret, "%s%u", p, c);
>
> Well, so the PAGE_SIZE boundary is never checked for this stacking write 
> now, right?

^^^ not really clear what I mean, so:

If you advance buf by ret every time, sysfs_emit() still would only 
check if buf is not written more than "PAGE_SIZE" bytes. But the 
original code performs this proper "PAGE_SIZE - ret" check.

> thanks,

--
js
suse labs