From: Julien Grall <julien@xen.org>
To: Jan Beulich <jbeulich@suse.com>
Cc: Julien Grall <jgrall@amazon.com>,
George Dunlap <george.dunlap@citrix.com>,
Dario Faggioli <dfaggioli@suse.com>,
xen-devel@lists.xenproject.org
Subject: Re: [PATCH 02/14] xen/sched: Constify name and opt_name in struct scheduler
Date: Tue, 6 Apr 2021 19:24:00 +0100 [thread overview]
Message-ID: <00a75c04-fad1-7061-ac39-a811f442db05@xen.org> (raw)
In-Reply-To: <5618bed6-a213-d2c9-4cbf-d95cb4dc02b4@suse.com>
Hi Jan,
On 06/04/2021 09:07, Jan Beulich wrote:
> On 05.04.2021 17:57, Julien Grall wrote:
>> From: Julien Grall <jgrall@amazon.com>
>>
>> Both name and opt_name are pointing to literal string. So mark both of
>> the fields as const.
>>
>> Signed-off-by: Julien Grall <jgrall@amazon.com>
>
> Reviewed-by: Jan Beulich <jbeulich@suse.com>
> albeit ...
>
>> --- a/xen/common/sched/private.h
>> +++ b/xen/common/sched/private.h
>> @@ -272,8 +272,8 @@ static inline spinlock_t *pcpu_schedule_trylock(unsigned int cpu)
>> }
>>
>> struct scheduler {
>> - char *name; /* full name for this scheduler */
>> - char *opt_name; /* option name for this scheduler */
>> + const char *name; /* full name for this scheduler */
>> + const char *opt_name; /* option name for this scheduler */
>
> ... I'd like to suggest considering at least the latter to become
> an array instead of a pointer - there's little point wasting 8
> bytes of storage for the pointer when the strings pointed to are
> all at most 9 bytes long (right now; I don't expect much longer
> ones to appear).
I have tried this simple/dumb change on top of my patch:
diff --git a/xen/common/sched/private.h b/xen/common/sched/private.h
index a870320146ef..ab2236874217 100644
--- a/xen/common/sched/private.h
+++ b/xen/common/sched/private.h
@@ -273,7 +273,7 @@ static inline spinlock_t
*pcpu_schedule_trylock(unsigned int cpu)
struct scheduler {
const char *name; /* full name for this scheduler */
- const char *opt_name; /* option name for this scheduler */
+ const char opt_name[9]; /* option name for this scheduler */
unsigned int sched_id; /* ID for this scheduler */
void *sched_data; /* global data pointer */
struct cpupool *cpupool;/* points to this scheduler's pool */
GCC will throw an error:
core.c: In function ‘scheduler_init’:
core.c:2987:17: error: assignment of read-only variable ‘ops’
ops = *schedulers[i];
^
core.c:2997:21: error: assignment of read-only variable ‘ops’
ops = *schedulers[i];
^
I don't particularly want to drop the const. So the code would probably
need some rework.
My patch doesn't change the size of the structure, so I would prefer to
keep this patch as-is.
Cheers,
--
Julien Grall
next prev parent reply other threads:[~2021-04-06 18:24 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-05 15:56 [PATCH 00/14] Use const whether we point to literal strings (take 1) Julien Grall
2021-04-05 15:57 ` [PATCH 01/14] xen: Constify the second parameter of rangeset_new() Julien Grall
2021-04-06 7:57 ` Jan Beulich
2021-04-06 18:03 ` Julien Grall
2021-04-05 15:57 ` [PATCH 02/14] xen/sched: Constify name and opt_name in struct scheduler Julien Grall
2021-04-06 8:07 ` Jan Beulich
2021-04-06 18:24 ` Julien Grall [this message]
2021-04-07 8:22 ` Jan Beulich
2021-04-07 9:06 ` Julien Grall
2021-04-06 14:19 ` George Dunlap
2021-04-05 15:57 ` [PATCH 03/14] xen/x86: shadow: The return type of sh_audit_flags() should be const Julien Grall
2021-04-06 7:24 ` Roger Pau Monné
2021-04-06 18:26 ` Julien Grall
2021-04-06 14:00 ` Tim Deegan
2021-04-05 15:57 ` [PATCH 04/14] xen/char: console: Use const whenever we point to literal strings Julien Grall
2021-04-06 8:10 ` Jan Beulich
2021-04-06 18:27 ` Julien Grall
2021-04-05 15:57 ` [PATCH 05/14] tools/libs: guest: " Julien Grall
2021-05-11 14:58 ` Anthony PERARD
2021-05-18 13:33 ` Julien Grall
2021-04-05 15:57 ` [PATCH 06/14] tools/libs: stat: " Julien Grall
2021-05-11 15:03 ` Anthony PERARD
2021-04-05 15:57 ` [PATCH 07/14] tools/xl: " Julien Grall
2021-04-27 16:04 ` Anthony PERARD
2021-04-27 16:28 ` Julien Grall
2021-04-27 17:03 ` Anthony PERARD
2021-04-05 15:57 ` [PATCH 08/14] tools/firmware: hvmloader: Use const in __bug() and __assert_failed() Julien Grall
2021-04-06 7:29 ` Roger Pau Monné
2021-04-06 19:02 ` Julien Grall
2021-04-05 15:57 ` [PATCH 09/14] tools/console: Use const whenever we point to literal strings Julien Grall
2021-05-11 15:18 ` Anthony PERARD
2021-05-18 13:48 ` Julien Grall
2021-04-05 15:57 ` [PATCH 10/14] tools/kdd: " Julien Grall
2021-04-06 14:03 ` Tim Deegan
2021-04-05 15:57 ` [PATCH 11/14] tools/misc: " Julien Grall
2021-05-11 15:37 ` Anthony PERARD
2021-04-05 15:57 ` [PATCH 12/14] tools/top: The string parameter in set_prompt() and set_delay() should be const Julien Grall
2021-05-11 15:46 ` Anthony PERARD
2021-04-05 15:57 ` [PATCH 13/14] tools/xenmon: xenbaked: Mark const the field text in stat_map_t Julien Grall
2021-05-11 16:08 ` Anthony PERARD
2021-04-05 15:57 ` [PATCH 14/14] tools/xentrace: Use const whenever we point to literal strings Julien Grall
2021-04-06 14:15 ` George Dunlap
2021-04-05 17:01 ` [PATCH 00/14] Use const whether we point to literal strings (take 1) Elliott Mitchell
2021-04-06 17:55 ` Julien Grall
2021-04-06 7:50 ` Jan Beulich
2021-04-06 19:08 ` Julien Grall
2021-05-10 17:49 ` PING " Julien Grall
2021-05-17 18:41 ` Wei Liu
2021-05-18 14:02 ` Julien Grall
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