linux-kernel - [patch V2 13/13] ptp: Simplify ptp

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Message-ID: <20250625115133.486953538@linutronix.de>
Date: Wed, 25 Jun 2025 13:52:39 +0200 (CEST)
From: Thomas Gleixner <tglx@...utronix.de>
To: LKML <linux-kernel@...r.kernel.org>
Cc: Richard Cochran <richardcochran@...il.com>,
 netdev@...r.kernel.org,
 Vadim Fedorenko <vadim.fedorenko@...ux.dev>,
 Paolo Abeni <pabeni@...hat.com>,
 Jakub Kicinski <kuba@...nel.org>
Subject: [patch V2 13/13] ptp: Simplify ptp_read()

The mixture of gotos and direct return codes is inconsistent and just makes
the code harder to read. Let it consistently return error codes directly and
tidy the code flow up accordingly.

No functional change intended.

Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
---
V2: Fix the return value - Paolo
    Drop the __free() part - Jakub
---
 drivers/ptp/ptp_chardev.c |   54 +++++++++++++---------------------------------
 1 file changed, 16 insertions(+), 38 deletions(-)

--- a/drivers/ptp/ptp_chardev.c
+++ b/drivers/ptp/ptp_chardev.c
@@ -106,8 +106,7 @@ int ptp_set_pinfunc(struct ptp_clock *pt
 
 int ptp_open(struct posix_clock_context *pccontext, fmode_t fmode)
 {
-	struct ptp_clock *ptp =
-		container_of(pccontext->clk, struct ptp_clock, clock);
+	struct ptp_clock *ptp = container_of(pccontext->clk, struct ptp_clock, clock);
 	struct timestamp_event_queue *queue;
 	char debugfsname[32];
 
@@ -536,67 +535,46 @@ long ptp_ioctl(struct posix_clock_contex
 ssize_t ptp_read(struct posix_clock_context *pccontext, uint rdflags,
 		 char __user *buf, size_t cnt)
 {
-	struct ptp_clock *ptp =
-		container_of(pccontext->clk, struct ptp_clock, clock);
+	struct ptp_clock *ptp =	container_of(pccontext->clk, struct ptp_clock, clock);
 	struct timestamp_event_queue *queue;
 	struct ptp_extts_event *event;
-	int result;
+	ssize_t result;
 
 	queue = pccontext->private_clkdata;
-	if (!queue) {
-		result = -EINVAL;
-		goto exit;
-	}
+	if (!queue)
+		return -EINVAL;
 
-	if (cnt % sizeof(struct ptp_extts_event) != 0) {
-		result = -EINVAL;
-		goto exit;
-	}
+	if (cnt % sizeof(*event) != 0)
+		return -EINVAL;
 
 	if (cnt > EXTTS_BUFSIZE)
 		cnt = EXTTS_BUFSIZE;
 
-	cnt = cnt / sizeof(struct ptp_extts_event);
-
-	if (wait_event_interruptible(ptp->tsev_wq,
-				     ptp->defunct || queue_cnt(queue))) {
+	if (wait_event_interruptible(ptp->tsev_wq, ptp->defunct || queue_cnt(queue)))
 		return -ERESTARTSYS;
-	}
 
-	if (ptp->defunct) {
-		result = -ENODEV;
-		goto exit;
-	}
+	if (ptp->defunct)
+		return -ENODEV;
 
 	event = kmalloc(EXTTS_BUFSIZE, GFP_KERNEL);
-	if (!event) {
-		result = -ENOMEM;
-		goto exit;
-	}
+	if (!event)
+		return -ENOMEM;
 
 	scoped_guard(spinlock_irq, &queue->lock) {
-		size_t qcnt = queue_cnt(queue);
-
-		if (cnt > qcnt)
-			cnt = qcnt;
+		size_t qcnt = min((size_t)queue_cnt(queue), cnt / sizeof(*event));
 
-		for (size_t i = 0; i < cnt; i++) {
+		for (size_t i = 0; i < qcnt; i++) {
 			event[i] = queue->buf[queue->head];
 			/* Paired with READ_ONCE() in queue_cnt() */
 			WRITE_ONCE(queue->head, (queue->head + 1) % PTP_MAX_TIMESTAMPS);
 		}
+		cnt = qcnt * sizeof(*event);
 	}
 
-	cnt = cnt * sizeof(struct ptp_extts_event);
-
 	result = cnt;
-	if (copy_to_user(buf, event, cnt)) {
+	if (copy_to_user(buf, event, cnt))
 		result = -EFAULT;
-		goto free_event;
-	}
 
-free_event:
 	kfree(event);
-exit:
 	return result;
 }