Messages in this thread Patch in this message | | | Date | Sat, 17 May 2014 17:44:28 +0200 | From | Mateusz Guzik <> | Subject | Re: [PATCH] fs: Cleanup string initializations (char[] instead of char *) |
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On Sat, May 17, 2014 at 05:00:18PM +0200, Manuel Schölling wrote: > Initializations like 'char *foo = "bar"' will create two variables: a static > string and a pointer (foo) to that static string. Instead 'char foo[] = "bar"' > will declare a single variable and will end up in shorter > assembly (according to Jeff Garzik on the KernelJanitor's TODO list). >
This is a greatly oversimplifying things, this may or may not happen.
Out of curiosity I checked my kernel on x86-64 and it has this optimized:
0xffffffffa00a9629 <bm_entry_read+121>: movabs $0x203a7367616c66,%rcx crash> ascii 0x203a7367616c66 00203a7367616c66: flags: <NUL>
> fs/binfmt_misc.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/fs/binfmt_misc.c b/fs/binfmt_misc.c > index b605003..2a10529 100644 > --- a/fs/binfmt_misc.c > +++ b/fs/binfmt_misc.c > @@ -419,7 +419,7 @@ static void entry_status(Node *e, char *page) > { > char *dp; > char *status = "disabled"; > - const char * flags = "flags: "; > + const char flags[] = "flags: "; > > if (test_bit(Enabled, &e->flags)) > status = "enabled";
This particular function would be better of with removing this variable and replacing all pairs like: sprintf(dp, ...); dp += strlen(...)
with: dp += sprintf(dp, ...);
-- Mateusz Guzik -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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