linux-kernel - [PATCH v2 4/4] eventfd: make eventfd_signal{

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Message-Id: <20231122-vfs-eventfd-signal-v2-4-bd549b14ce0c@kernel.org>
Date:   Wed, 22 Nov 2023 13:48:25 +0100
From:   Christian Brauner <brauner@...nel.org>
To:     linux-fsdevel@...r.kernel.org
Cc:     Christoph Hellwig <hch@....de>, Jan Kara <jack@...e.cz>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
        David Woodhouse <dwmw2@...radead.org>,
        Paul Durrant <paul@....org>, Oded Gabbay <ogabbay@...nel.org>,
        Wu Hao <hao.wu@...el.com>, Tom Rix <trix@...hat.com>,
        Moritz Fischer <mdf@...nel.org>, Xu Yilun <yilun.xu@...el.com>,
        Zhenyu Wang <zhenyuw@...ux.intel.com>,
        Zhi Wang <zhi.a.wang@...el.com>,
        Jani Nikula <jani.nikula@...ux.intel.com>,
        Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
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        Benjamin LaHaise <bcrl@...ck.org>,
        Christian Brauner <brauner@...nel.org>,
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Subject: [PATCH v2 4/4] eventfd: make eventfd_signal{_mask}() void

No caller care about the return value.

Signed-off-by: Christian Brauner <brauner@...nel.org>
---
 fs/eventfd.c            | 40 +++++++++++++++-------------------------
 include/linux/eventfd.h | 16 +++++++---------
 2 files changed, 22 insertions(+), 34 deletions(-)

diff --git a/fs/eventfd.c b/fs/eventfd.c
index a9a6de920fb4..13be2fb7fc96 100644
--- a/fs/eventfd.c
+++ b/fs/eventfd.c
@@ -43,10 +43,19 @@ struct eventfd_ctx {
 	int id;
 };
 
-__u64 eventfd_signal_mask(struct eventfd_ctx *ctx, __poll_t mask)
+/**
+ * eventfd_signal - Adds @n to the eventfd counter.
+ * @ctx: [in] Pointer to the eventfd context.
+ * @mask: [in] poll mask
+ *
+ * This function is supposed to be called by the kernel in paths that do not
+ * allow sleeping. In this function we allow the counter to reach the ULLONG_MAX
+ * value, and we signal this as overflow condition by returning a EPOLLERR
+ * to poll(2).
+ */
+void eventfd_signal_mask(struct eventfd_ctx *ctx, __poll_t mask)
 {
 	unsigned long flags;
-	__u64 n = 1;
 
 	/*
 	 * Deadlock or stack overflow issues can happen if we recurse here
@@ -57,37 +66,18 @@ __u64 eventfd_signal_mask(struct eventfd_ctx *ctx, __poll_t mask)
 	 * safe context.
 	 */
 	if (WARN_ON_ONCE(current->in_eventfd))
-		return 0;
+		return;
 
 	spin_lock_irqsave(&ctx->wqh.lock, flags);
 	current->in_eventfd = 1;
-	if (ULLONG_MAX - ctx->count < n)
-		n = ULLONG_MAX - ctx->count;
-	ctx->count += n;
+	if (ctx->count < ULLONG_MAX)
+		ctx->count++;
 	if (waitqueue_active(&ctx->wqh))
 		wake_up_locked_poll(&ctx->wqh, EPOLLIN | mask);
 	current->in_eventfd = 0;
 	spin_unlock_irqrestore(&ctx->wqh.lock, flags);
-
-	return n == 1;
-}
-
-/**
- * eventfd_signal - Adds @n to the eventfd counter.
- * @ctx: [in] Pointer to the eventfd context.
- *
- * This function is supposed to be called by the kernel in paths that do not
- * allow sleeping. In this function we allow the counter to reach the ULLONG_MAX
- * value, and we signal this as overflow condition by returning a EPOLLERR
- * to poll(2).
- *
- * Returns the amount by which the counter was incremented.
- */
-__u64 eventfd_signal(struct eventfd_ctx *ctx)
-{
-	return eventfd_signal_mask(ctx, 0);
 }
-EXPORT_SYMBOL_GPL(eventfd_signal);
+EXPORT_SYMBOL_GPL(eventfd_signal_mask);
 
 static void eventfd_free_ctx(struct eventfd_ctx *ctx)
 {
diff --git a/include/linux/eventfd.h b/include/linux/eventfd.h
index 4f8aac7eb62a..fea7c4eb01d6 100644
--- a/include/linux/eventfd.h
+++ b/include/linux/eventfd.h
@@ -35,8 +35,7 @@ void eventfd_ctx_put(struct eventfd_ctx *ctx);
 struct file *eventfd_fget(int fd);
 struct eventfd_ctx *eventfd_ctx_fdget(int fd);
 struct eventfd_ctx *eventfd_ctx_fileget(struct file *file);
-__u64 eventfd_signal(struct eventfd_ctx *ctx);
-__u64 eventfd_signal_mask(struct eventfd_ctx *ctx, __poll_t mask);
+void eventfd_signal_mask(struct eventfd_ctx *ctx, __poll_t mask);
 int eventfd_ctx_remove_wait_queue(struct eventfd_ctx *ctx, wait_queue_entry_t *wait,
 				  __u64 *cnt);
 void eventfd_ctx_do_read(struct eventfd_ctx *ctx, __u64 *cnt);
@@ -58,14 +57,8 @@ static inline struct eventfd_ctx *eventfd_ctx_fdget(int fd)
 	return ERR_PTR(-ENOSYS);
 }
 
-static inline int eventfd_signal(struct eventfd_ctx *ctx)
+static inline void eventfd_signal_mask(struct eventfd_ctx *ctx, unsigned mask)
 {
-	return -ENOSYS;
-}
-
-static inline int eventfd_signal_mask(struct eventfd_ctx *ctx, unsigned mask)
-{
-	return -ENOSYS;
 }
 
 static inline void eventfd_ctx_put(struct eventfd_ctx *ctx)
@@ -91,5 +84,10 @@ static inline void eventfd_ctx_do_read(struct eventfd_ctx *ctx, __u64 *cnt)
 
 #endif
 
+static inline void eventfd_signal(struct eventfd_ctx *ctx)
+{
+	eventfd_signal_mask(ctx, 0);
+}
+
 #endif /* _LINUX_EVENTFD_H */
 

-- 
2.42.0