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Message-Id: <1628051945.fens3r99ox.astroid@bobo.none>
Date: Wed, 04 Aug 2021 14:59:23 +1000
From: Nicholas Piggin <npiggin@...il.com>
To: linux-kernel@...r.kernel.org, Randy Dunlap <rdunlap@...radead.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
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?
--
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);
--
2.23.0
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