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From: "Sébastien Dugué" <sebastien.dugue@bull.net>
To: Zach Brown <zach.brown@oracle.com>
Cc: linux-kernel <linux-kernel@vger.kernel.org>,
linux-aio <linux-aio@kvack.org>, Andrew Morton <akpm@osdl.org>,
Suparna Bhattacharya <suparna@in.ibm.com>,
Christoph Hellwig <hch@infradead.org>,
Badari Pulavarty <pbadari@us.ibm.com>,
Ulrich Drepper <drepper@redhat.com>,
Jean Pierre Dion <jean-pierre.dion@bull.net>
Subject: Re: [PATCH -mm 1/5][AIO] - Rework compat_sys_io_submit
Date: Thu, 30 Nov 2006 10:57:10 +0100 [thread overview]
Message-ID: <20061130105710.572d3c6e@frecb000686> (raw)
In-Reply-To: <8BA392C6-FCCB-40BD-9CCF-3EF56C3491BD@oracle.com>
On Wed, 29 Nov 2006 16:47:47 -0800, Zach Brown <zach.brown@oracle.com> wrote:
> On Nov 29, 2006, at 2:32 AM, Sébastien Dugué wrote:
>
> > compat_sys_io_submit() cleanup
> >
> >
> > Cleanup compat_sys_io_submit by duplicating some of the native
> > syscall
> > logic in the compat layer and directly calling io_submit_one() instead
> > of fooling the syscall into thinking it is called from a native 64-bit
> > caller.
> >
> > This is needed for the completion notification patch to avoid having
> > to rewrite each iocb on the caller stack for sys_io_submit() to
> > find the
> > sigevents.
>
> You could explicitly mention that this eliminates:
>
> - the overhead of copying nr pointers on the userspace caller's stack
>
> - the arbitrary PAGE_SIZE/(sizeof(void *)) limit on the number of
> iocbs that can be submitted
>
> Those alone make this worth merging.
Right, will add.
>
> > + if (unlikely(!access_ok(VERIFY_READ, iocb, (nr * sizeof(u32)))))
> > + return -EFAULT;
>
> I'm glad you got that right :) I no doubt would have initially
> hoisted these little checks into a shared helper function and missed
> that detail of getting the size of the access_ok() right in the
> compat case.
Thanks.
>
> > + put_ioctx(ctx);
> > +
> > + return i? i: ret;
>
> sys_io_getevents() reads:
uh! ^^^^^^^^^ you must be meaning sys_io_submit()?
>
> put_ioctx(ctx);
> return i ? i : ret;
>
> So while this compat_sys_io_submit() logic seems fine and I would be
> comfortable with it landing as-is, I'd also appreciate it if we
> didn't introduce differences between the two functions when it seems
> just as easy to make them the same. (That chunk is just one
> example. There's whitespace, missing unlikely()s, etc).
>
OK, will fix.
Thanks,
Sébastien.
next prev parent reply other threads:[~2006-11-30 9:58 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-11-29 10:24 [PATCH -mm 0/5][AIO] - AIO completion signal notification v3 Sébastien Dugué
2006-11-29 10:32 ` [PATCH -mm 1/5][AIO] - Rework compat_sys_io_submit Sébastien Dugué
2006-11-30 0:47 ` Zach Brown
2006-11-30 9:57 ` Sébastien Dugué [this message]
2006-11-30 17:27 ` Zach Brown
2006-11-29 10:32 ` [PATCH -mm 2/5][AIO] - fix aio.h includes Sébastien Dugué
2006-11-29 10:32 ` [PATCH -mm 3/5][AIO] - export good_sigevent() Sébastien Dugué
2006-11-29 10:38 ` Christoph Hellwig
2006-11-29 10:46 ` Sébastien Dugué
2006-11-29 14:54 ` Christoph Hellwig
2006-11-29 16:10 ` Sébastien Dugué
2006-12-04 17:13 ` Bharata B Rao
2006-12-05 8:30 ` Sébastien Dugué
2006-11-29 10:33 ` [PATCH -mm 4/5][AIO] - AIO completion signal notification Sébastien Dugué
2006-11-29 10:51 ` Christoph Hellwig
2006-11-29 13:08 ` Sébastien Dugué
2006-11-29 13:50 ` Christoph Hellwig
2006-11-29 14:18 ` Sébastien Dugué
2006-11-29 11:33 ` Jakub Jelinek
2006-11-29 13:25 ` Sébastien Dugué
2006-11-29 10:33 ` [PATCH -mm 5/5][AIO] - Listio support Sébastien Dugué
2006-11-30 8:25 ` Suparna Bhattacharya
2006-11-30 10:04 ` Sébastien Dugué
2006-11-30 15:38 [PATCH -mm 0/5][AIO] - AIO completion signal notification v4 Sébastien Dugué
2006-11-30 15:49 ` [PATCH -mm 1/5][AIO] - Rework compat_sys_io_submit Sébastien Dugué
[not found] <20070117104601.36b2ab18@frecb000686>
2007-01-17 9:48 ` Sébastien Dugué
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