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Message-ID: <06ea8c29-ed66-7014-53bd-7760b7eac632@infradead.org>
Date: Tue, 3 Aug 2021 22:09:02 -0700
From: Randy Dunlap <rdunlap@...radead.org>
To: Nicholas Piggin <npiggin@...il.com>, linux-kernel@...r.kernel.org
Cc: Andrew Morton <akpm@...ux-foundation.org>,
Mark Brown <broonie@...nel.org>
Subject: Re: [PATCH -next/-mmotm] kernel/user.c: fix build when POLL not
enabled
On 8/3/21 9:59 PM, Nicholas Piggin wrote:
> Excerpts from Randy Dunlap's message of August 4, 2021 6:46 am:
>> Fix build errors in kernel/user.c when CONFIG_EPOLL is not set/enabled.
>>
>> ../kernel/user.c: In function ‘free_user’:
>> ../kernel/user.c:141:30: error: ‘struct user_struct’ has no member named ‘epoll_watches’; did you mean ‘nr_watches’?
>> percpu_counter_destroy(&up->epoll_watches);
>> ^~~~~~~~~~~~~
>> In file included from ../include/linux/sched/user.h:7:0,
>> from ../kernel/user.c:17:
>> ../kernel/user.c: In function ‘alloc_uid’:
>> ../kernel/user.c:189:33: error: ‘struct user_struct’ has no member named ‘epoll_watches’; did you mean ‘nr_watches’?
>> if (percpu_counter_init(&new->epoll_watches, 0, GFP_KERNEL)) {
>> ^
>> ../kernel/user.c:203:33: error: ‘struct user_struct’ has no member named ‘epoll_watches’; did you mean ‘nr_watches’?
>> percpu_counter_destroy(&new->epoll_watches);
>> ^~~~~~~~~~~~~
>> In file included from ../include/linux/sched/user.h:7:0,
>> from ../kernel/user.c:17:
>> ../kernel/user.c: In function ‘uid_cache_init’:
>> ../kernel/user.c:225:37: error: ‘struct user_struct’ has no member named ‘epoll_watches’; did you mean ‘nr_watches’?
>> if (percpu_counter_init(&root_user.epoll_watches, 0, GFP_KERNEL))
>> ^
>> Also fix type: "cpunter" -> "counter" in a panic message.
>
> Gah, thanks Randy. The ifdefs aren't horrible but could I suggest a
> slight tweak?
Sure, no problem. Thanks.
>
> --
> From: Randy Dunlap <rdunlap@...radead.org>
> Subject: [PATCH] kernel/user.c: fix build when EPOLL not enabled
>
> Fix build errors in kernel/user.c when CONFIG_EPOLL is not set/enabled.
>
> ../kernel/user.c: In function ‘free_user’:
> ../kernel/user.c:141:30: error: ‘struct user_struct’ has no member named ‘epoll_watches’; did you mean ‘nr_watches’?
> percpu_counter_destroy(&up->epoll_watches);
> ^~~~~~~~~~~~~
> In file included from ../include/linux/sched/user.h:7:0,
> from ../kernel/user.c:17:
> ../kernel/user.c: In function ‘alloc_uid’:
> ../kernel/user.c:189:33: error: ‘struct user_struct’ has no member named ‘epoll_watches’; did you mean ‘nr_watches’?
> if (percpu_counter_init(&new->epoll_watches, 0, GFP_KERNEL)) {
> ^
> ../kernel/user.c:203:33: error: ‘struct user_struct’ has no member named ‘epoll_watches’; did you mean ‘nr_watches’?
> percpu_counter_destroy(&new->epoll_watches);
> ^~~~~~~~~~~~~
> In file included from ../include/linux/sched/user.h:7:0,
> from ../kernel/user.c:17:
> ../kernel/user.c: In function ‘uid_cache_init’:
> ../kernel/user.c:225:37: error: ‘struct user_struct’ has no member named ‘epoll_watches’; did you mean ‘nr_watches’?
> if (percpu_counter_init(&root_user.epoll_watches, 0, GFP_KERNEL))
> ^
> Also fix type: "cpunter" -"counter" in a panic message.
>
> Fixes: e75b89477811 ("fs/epoll: use a per-cpu counter for user's watches count")
> Signed-off-by: Randy Dunlap <rdunlap@...radead.org>
> [np: move ifdefs into wrapper functions, slightly improve panic message]
> Signed-off-by: Nicholas Piggin <npiggin@...il.com>
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> Cc: Nick Piggin <npiggin@...il.com>
> Cc: Mark Brown <broonie@...nel.org>
> ---
> kernel/user.c | 25 ++++++++++++++++++++-----
> 1 file changed, 20 insertions(+), 5 deletions(-)
>
> diff --git a/kernel/user.c b/kernel/user.c
> index a2673f940506..57d53568cb33 100644
> --- a/kernel/user.c
> +++ b/kernel/user.c
> @@ -129,6 +129,21 @@ static struct user_struct *uid_hash_find(kuid_t uid, struct hlist_head *hashent)
> return NULL;
> }
>
> +static int user_epoll_alloc(struct user_struct *up)
> +{
> +#ifdef CONFIG_EPOLL
> + return percpu_counter_init(&up->epoll_watches, 0, GFP_KERNEL);
> +#endif
> + return 0;
> +}
> +
> +static void user_epoll_free(struct user_struct *up)
> +{
> +#ifdef CONFIG_EPOLL
> + percpu_counter_destroy(&up->epoll_watches);
> +#endif
> +}
> +
> /* IRQs are disabled and uidhash_lock is held upon function entry.
> * IRQ state (as stored in flags) is restored and uidhash_lock released
> * upon function exit.
> @@ -138,7 +153,7 @@ static void free_user(struct user_struct *up, unsigned long flags)
> {
> uid_hash_remove(up);
> spin_unlock_irqrestore(&uidhash_lock, flags);
> - percpu_counter_destroy(&up->epoll_watches);
> + user_epoll_free(up);
> kmem_cache_free(uid_cachep, up);
> }
>
> @@ -186,7 +201,7 @@ struct user_struct *alloc_uid(kuid_t uid)
>
> new->uid = uid;
> refcount_set(&new->__count, 1);
> - if (percpu_counter_init(&new->epoll_watches, 0, GFP_KERNEL)) {
> + if (user_epoll_alloc(new)) {
> kmem_cache_free(uid_cachep, new);
> return NULL;
> }
> @@ -200,7 +215,7 @@ struct user_struct *alloc_uid(kuid_t uid)
> spin_lock_irq(&uidhash_lock);
> up = uid_hash_find(uid, hashent);
> if (up) {
> - percpu_counter_destroy(&new->epoll_watches);
> + user_epoll_free(new);
> kmem_cache_free(uid_cachep, new);
> } else {
> uid_hash_insert(new, hashent);
> @@ -222,8 +237,8 @@ static int __init uid_cache_init(void)
> for(n = 0; n < UIDHASH_SZ; ++n)
> INIT_HLIST_HEAD(uidhash_table + n);
>
> - if (percpu_counter_init(&root_user.epoll_watches, 0, GFP_KERNEL))
> - panic("percpu cpunter alloc failed");
> + if (user_epoll_alloc(&root_user))
> + panic("root_user epoll percpu counter alloc failed");
>
> /* Insert the root user immediately (init already runs as root) */
> spin_lock_irq(&uidhash_lock);
>
--
~Randy
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