Re: [PATCH] Drop second arg of unregister_chrdev()
From: Alexey Dobriyan
Date: Tue Aug 15 2006 - 00:20:30 EST
On Mon, Aug 14, 2006 at 08:48:17PM -0700, Andrew Morton wrote:
> On Tue, 15 Aug 2006 07:35:22 +0400
> Alexey Dobriyan <adobriyan@xxxxxxxxx> wrote:
> > * "name" is trivially unused.
> > * Requirement to pass to unregister function anything but cookie you've
> > got from register counterpart is wrong. It creates opportunity to
> > diverge, it create opportunity for bugs if enforced:
> > /*
> > * XXX(hch): bp->b_count_desired might be incorrect (see
> > * xfs_buf_associate_memory for details),
> > Signed-off-by: Alexey Dobriyan <adobriyan@xxxxxxxxx>
> > * but fortunately
> > * the Linux version of kmem_free ignores the len argument..
> > */
> > kmem_free(bp->b_addr, bp->b_count_desired);
> I don't understand that.
p = malloc(size);
is good. You don't have to remember "size" which sometimes nontrivially
calculated until free time.
mmio = ioremap(start, size);
is good too for same reasons. Agree so far?
major = register_chrdev(0, "foo", &foo_fops);
is good too even if people don't forget to pass the same "foo" in two
places. Luckily, unregister_chrdev() ignores name arg, so passing wrong
won't do any harm.
> > 64 files changed, 97 insertions(+), 97 deletions(-)
> I do understand that. This'll cause some grief.
In kernel, hardly...
$ grep unregister_chrdev -w -n 2.6.18-rc4-mm1
33126: unregister_chrdev(CPUID_MAJOR, "cpu/cpuid");
35853: unregister_chrdev(MSR_MAJOR, "cpu/msr");
35861: unregister_chrdev(MSR_MAJOR, "cpu/msr");
134610: unregister_chrdev(LP_MAJOR, "lp");
291207:- unregister_chrdev(hptiop_cdev_major, "hptiop");
352167:+ unregister_chrdev(major_number, "SerialQT_USB");
Two rejects, 4 fuzzy places.
> I'd suggest that we add a
> new unregister_char_dev() or something, and do
But there is register_CHRDEV_region, unregister_CHRDEV_region,
alloc_CHRDEV_region, register_CHRDEV. Should I change the spelling of
register_chrdev() for a good measure, too?
> static inline unregister_chrdev(unsigned int major, const char *name)
> return unregister_char_dev(major);
> then migrate callers over to unregister_char_dev() in an organised fashion,
> via maintainers where poss.
> Then mark unregister_chrdev() deprecated for a while.
> Then nuke it.
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