From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-ed1-f46.google.com (mail-ed1-f46.google.com [209.85.208.46]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9C7C83FDBE7 for ; Wed, 5 Aug 2026 09:35:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.208.46 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785922550; cv=none; b=XiY7CJxIAx3XL6tCnToIY4Yda0t99Da4MAibdmNY1EAkxonJy8aNr4LhFZN6BaqoxZVmRQWkLQoEDWXL0fHwZi1ZBNLwOVnpCEC5fyKXfRYMtC3em75fa2z43LX3D967l3h26CUPe/m6eT2ogn4lzkB/M+ZMjf0Zyi5TDb6iRY8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785922550; c=relaxed/simple; bh=p+p8W4MgN9b8RWWgCixK+8EJrMWDnZxeABj4CHUbl9c=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References; b=UFjDW8VZGfyGdbDQ6lMXnxYMuTLFXCxlOfiV9T2vIYPScsEKM42si1HkGB36wJS3sT4ekCEdSmvO2Ece2X/5CQc2FBUIuKfZZe2+Fo+lMtveY+z9wQ6UO1ggAP3GtgxYdTLDnkJoVozM6w4uNyJ2SOl36frxe0Zk1cX+g/U1eD0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=oZSdI0g6; arc=none smtp.client-ip=209.85.208.46 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="oZSdI0g6" Received: by mail-ed1-f46.google.com with SMTP id 4fb4d7f45d1cf-6a14f762de4so930280a12.0 for ; Wed, 05 Aug 2026 02:35:48 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1785922547; x=1786527347; darn=vger.kernel.org; h=references:in-reply-to:message-id:date:subject:cc:to:from:from:to :cc:subject:date:message-id:reply-to:content-type; bh=DcNVtLGy4fr4mNMQ0zx7myIqGPoEGYnS3E48RlqOqW4=; b=oZSdI0g68xGUV1opKsPxZNqNDfUttAXROTzKUIGWK97pt8U/bpBwiKbxhY/7PsjItm 9SonLkqtinQ70IZxNGxqyaNPliPAYPJjhAPwgin6KPFe7IotqQLJItsy3y9Qxe1o6DDe DfAyf/JAQBEwqRUaCW0ibyrriIy9LtABKA6fijJepcnkl3bbI4A/jpOO3hXsWbFG/osz d7ITQ2HRWpQnVP/Y0Qj6Q1QVrvwUXrzYuJCoQoqcHjwqWrAV8zK7ug2cx8nnr3sPs6ti xj8pYZMqSYZnZck5bUZd+nvA50ik5Q5lS/FIhdX1iNEU8GX1EyX1QSVtpVsucTn2ZPs1 uyBw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1785922547; x=1786527347; h=references:in-reply-to:message-id:date:subject:cc:to:from:x-gm-gg :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=DcNVtLGy4fr4mNMQ0zx7myIqGPoEGYnS3E48RlqOqW4=; b=LTKJoY9N7oQvTdaW4Ju848GCWw3qCbIgM7TRD2MVWnlyywRQpNLpbrtJG1O9MSxJLu TXhuwlG3w+TU9GxaDBNu1x6e5jOX1SgRjOFTYav/lQAFTYl/4HMVI/D+pY/MxNK5RQwA KBylqAoPecFfyQyHUqBGDarouhBQaVXqV1UOM+ctJyt7nFh/B2lEEwclu/UptbdjT3o6 zRHviVffH/v2XmxiU49M+4dZONHDstY38sCVdRbgCjk53L4AjNGjBwY2e4zxGpezgmT4 0qy/kmEEZ4LpvBOrfFjuAf955z+T51R/HJtItk8MWN/Ek2jbIRZ4CvqFI6bDjkvAsBYV IPPQ== X-Forwarded-Encrypted: i=1; AHgh+RrMFB9LOiQ7RDT5+CW+FG2sXUkV7bqWrk3fJ6tkNzJUi/2EOV2m3dknDd7hH19xK+sa6lWDzoKOgbR/7eU=@vger.kernel.org X-Gm-Message-State: AOJu0YyaZSwDRIuKj8mOVq4RbSlPUOpTJh4en95UXAmJRlKuwAghy3yB teSYLAg8aWjtEgGVFvN9MtDudaoUUrUNmOcY6qqc+FD1LlegBqSjhX0z X-Gm-Gg: AR+sD12BNrvM29o75scdcwoO6eO7XU4JgTsb1/qNeIk+woZ5COvM0BIXppMuqmuqpt4 h+VYCoDqjug+7TD6+KdRV2MW3M4vggVKbCAX2s7Bx/npSL9nLPs3VQWr1spW0HiIeCkNf1AikmS IqavQAryrZyTxTJQANspxiO7dm8TB7PvS5PGCy4IpSWOQr6AwlFUsxZzACPrTlHKnoGbLd0DcuL RiTsNEMoEsKHRi82V5UZPg34lT6WaewxYg6zgJuJZIToXwFD/Ci1TbIRGOb/bWkdkzG6DD5OAc2 Rz8XCyU6klXN0xaXpt0SUca9GyT4lKtyKwPQaIhdUFU5D7DUmQDZPDk8m1wD7RDV0pgQ5+MOA03 Sy9hSm0Sn8q4aGikVelGRlYqg9FyJXFpRULNiYdwjwQMPRG3Wv2AVF+FDtIOW05010Y27HlhDZa UBLjfqYz191KbFDKkFUa2oNIAIKRqkQyQ8o/i/s50HH8k8WDU+IFEL2k49zbU9z4S5azCjTux/r JiqhcoQuE+Pqhcn X-Received: by 2002:a17:907:d38b:b0:c16:13c3:b1ef with SMTP id a640c23a62f3a-c2039d1daabmr226716766b.24.1785922546673; Wed, 05 Aug 2026 02:35:46 -0700 (PDT) Received: from localhost (c-85-228-45-68.bbcust.telenor.se. [85.228.45.68]) by smtp.gmail.com with ESMTPSA id 4fb4d7f45d1cf-6a145de6d01sm1596561a12.18.2026.08.05.02.35.45 (version=TLS1_2 cipher=ECDHE-ECDSA-CHACHA20-POLY1305 bits=256/256); Wed, 05 Aug 2026 02:35:46 -0700 (PDT) From: Eli Billauer To: gregkh@linuxfoundation.org Cc: arnd@arndb.de, linux-kernel@vger.kernel.org, corbet@lwn.net, Eli Billauer Subject: [PATCH v4 4/7] char: xillybus: Use unsigned arithmetic for jiffies differences Date: Wed, 5 Aug 2026 11:34:33 +0200 Message-Id: <20260805093436.59740-5-eli.billauer@gmail.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20260805093436.59740-1-eli.billauer@gmail.com> References: <20260805093436.59740-1-eli.billauer@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Change the type of jiffies-related deadline variables from long to unsigned long, and remove unnecessary casts when computing time remaining as deadline - jiffies. No functional change is expected: although signed overflow is undefined in the C standard, processors perform the calculation correctly in practice. Using unsigned arithmetic is nevertheless the proper way to handle jiffies differences. Assisted-by: Deepseek:v4-pro Kimi:K2.6 ChatGPT:GPT-5.5 Claude:Sonnet-4.6 Signed-off-by: Eli Billauer --- Notes: Changelog: ========= No change on v3->v4. Changes v2->v3: -- Add Assisted-by tag to description No change on v1->v2. drivers/char/xillybus/xillybus_core.c | 5 +++-- drivers/char/xillybus/xillyusb.c | 17 ++++++++++------- 2 files changed, 13 insertions(+), 9 deletions(-) diff --git a/drivers/char/xillybus/xillybus_core.c b/drivers/char/xillybus/xillybus_core.c index 952ef149aba1..7acebc1e6050 100644 --- a/drivers/char/xillybus/xillybus_core.c +++ b/drivers/char/xillybus/xillybus_core.c @@ -694,7 +694,8 @@ static ssize_t xillybus_read(struct file *filp, char __user *userbuf, unsigned long flags; int bytes_done = 0; int no_time_left = 0; - long deadline, left_to_sleep; + unsigned long deadline; + long left_to_sleep; struct xilly_channel *channel = filp->private_data; int empty, reached_eof, exhausted, ready; @@ -938,7 +939,7 @@ static ssize_t xillybus_read(struct file *filp, char __user *userbuf, return -EINTR; } - left_to_sleep = deadline - ((long) jiffies); + left_to_sleep = deadline - jiffies; /* * If our time is out, skip the waiting. We may miss wr_sleepy diff --git a/drivers/char/xillybus/xillyusb.c b/drivers/char/xillybus/xillyusb.c index ef5b1816b277..e2270a64b659 100644 --- a/drivers/char/xillybus/xillyusb.c +++ b/drivers/char/xillybus/xillyusb.c @@ -1132,12 +1132,13 @@ static int xillyusb_send_opcode(struct xillyusb_dev *xdev, */ static int flush_downstream(struct xillyusb_channel *chan, - long timeout, + unsigned long timeout, bool interruptible) { struct xillyusb_dev *xdev = chan->xdev; int chan_num = chan->chan_idx << 1; - long deadline, left_to_sleep; + unsigned long deadline; + long left_to_sleep; int rc; if (chan->flushed) @@ -1146,7 +1147,8 @@ static int flush_downstream(struct xillyusb_channel *chan, deadline = jiffies + 1 + timeout; if (chan->flushing) { - long cancel_deadline = jiffies + 1 + XILLY_RESPONSE_TIMEOUT; + unsigned long cancel_deadline = + jiffies + 1 + XILLY_RESPONSE_TIMEOUT; chan->canceled = 0; rc = xillyusb_send_opcode(xdev, chan_num, @@ -1157,7 +1159,7 @@ static int flush_downstream(struct xillyusb_channel *chan, /* Ignoring interrupts. Cancellation must be handled */ while (!chan->canceled) { - left_to_sleep = cancel_deadline - ((long)jiffies); + left_to_sleep = cancel_deadline - jiffies; if (left_to_sleep <= 0) { report_io_error(xdev, -EIO); @@ -1207,7 +1209,7 @@ static int flush_downstream(struct xillyusb_channel *chan, } while (chan->flushing) { - left_to_sleep = deadline - ((long)jiffies); + left_to_sleep = deadline - jiffies; if (left_to_sleep <= 0) return -ETIMEDOUT; @@ -1440,7 +1442,8 @@ static ssize_t xillyusb_read(struct file *filp, char __user *userbuf, struct xillyfifo *fifo = chan->in_fifo; int chan_num = (chan->chan_idx << 1) | 1; - long deadline, left_to_sleep; + unsigned long deadline; + long left_to_sleep; int bytes_done = 0; bool sent_set_push = false; int rc; @@ -1469,7 +1472,7 @@ static ssize_t xillyusb_read(struct file *filp, char __user *userbuf, bytes_done += rc; chan->in_consumed_bytes += rc; - left_to_sleep = deadline - ((long)jiffies); + left_to_sleep = deadline - jiffies; /* * Some 32-bit arithmetic that may wrap. Note that -- 2.34.1