[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH] cleancache: constify cleancache_ops structure
On Thu, 21 Jan 2016, Rasmus Villemoes wrote: > On Wed, Jan 20 2016, Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> wrote: > > > On Wed, Dec 23, 2015 at 10:06:24PM +0100, Julia Lawall wrote: > >> The cleancache_ops structure is never modified, so declare it as const. > >> > >> This also removes the __read_mostly declaration on the cleancache_ops > >> variable declaration, since it seems redundant with const. > >> > >> Done with the help of Coccinelle. > >> > >> Signed-off-by: Julia Lawall <Julia.Lawall@xxxxxxx> > >> > >> --- > >> > >> Not sure that the __read_mostly change is correct. Does it apply to the > >> variable, or to what the variable points to? > > > > It should just put the structure in the right section (.rodata). > > > > Thanks for the patch! > > The __read_mostly marker should probably be left there... I sent a corrected version this afternoon. > > >> */ > >> -static struct cleancache_ops *cleancache_ops __read_mostly; > >> +static const struct cleancache_ops *cleancache_ops; > >> > >> /* > >> * Counters available via /sys/kernel/debug/cleancache (if debugfs is > >> @@ -49,7 +49,7 @@ static void cleancache_register_ops_sb(struct > >> super_block *sb, void *unused) > >> /* > >> * Register operations for cleancache. Returns 0 on success. > >> */ > >> -int cleancache_register_ops(struct cleancache_ops *ops) > >> +int cleancache_register_ops(const struct cleancache_ops *ops) > >> { > >> if (cmpxchg(&cleancache_ops, NULL, ops)) > >> return -EBUSY; > >> > > I don't know this code, but I assume that this is mostly a one-time > thing, so once cleancache_ops gets its value assigned, it doesn't > change, and that's what the __read_mostly is about (it applies to the > object declared, not whatever it happens to point to). > > (Also, the commit message is slightly inaccurate: it is > tmem_cleancache_ops which is never changed and hence declared const; > changing the various pointers to it to const is just a necessary followup). OK, in general, I have referred to the type rather than the structure name in these patches, since there can be more than one structure. julia _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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