From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wr1-f42.google.com (mail-wr1-f42.google.com [209.85.221.42]) (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 A7702311583 for ; Tue, 3 Feb 2026 11:49:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.221.42 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770119346; cv=none; b=UJkpWsUW/5Dkx2g450E4e9aMcFZbpxfnGYRnTR8NIhCVugwXMc+mWOGvF//gbaWJyE/d/ESa6rJbM3YJ2Mnyv93oDVwYNxqAnEZ+ri2z7+wkwFTw4poPmrLvnxxSMD+knliF+OT5aSHCKEXd36dJau47UlL/tGO0Yu/IHcsE8jE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770119346; c=relaxed/simple; bh=IqMRuouYKplCpuBL4+LEX/kT9JKSXiQib3OML5jseRI=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=adSTLdNe1HMdTHnu7tHnQImB0cNpFpSJRYJGlx0Nk7oKx4y1GgaH59Japd+GtZ1WE87BEoZ6QV88n3DZXZuxtFB+zqgD0/yyUOThdG0CpYR5xSlqoTApuPQIjhN5WAFDSlk1M80nfq2A5ZVfWR/Z1300yhLJBMBh2XUGQTZOkhY= 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=QifFsYX5; arc=none smtp.client-ip=209.85.221.42 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="QifFsYX5" Received: by mail-wr1-f42.google.com with SMTP id ffacd0b85a97d-42fbc544b09so5100456f8f.1 for ; Tue, 03 Feb 2026 03:49:04 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1770119343; x=1770724143; darn=lists.linux.dev; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=Z4FvJLpGt0rg4WG2VihKDDJ7LuQY5vf0sYtnb+B7S6Q=; b=QifFsYX57BLSWWNOVpglKn5Dzpd3wgULE6Gog3+sokPqmHJazIt97pTNuJNt5sWuyV L5NautxrE5ty7lhNmcYBOC6OzzGtwgbEORurQ0rkAmxkjbmjFgXl5eXZbc3O9J2X044+ PcsVeorWk7mNZDd4LEeIhus5v0c6dUuq7sS5Hk9tpAUvQVHconKzSCT1pSJ4+lc0wLyK HDCKjea33gjHCx2s3DxGUcV+Zp9RF2h7nK7Jnwa9qZEQNtWtEgYinD53Cm6vwlxfUkEJ QfLLlbDMn0W4QrSTykEw5U8uHvwqm5IR7gx59vvRY4W3dvpz1QOXRSkOpnIlMR5Ukx1o gSDw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1770119343; x=1770724143; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=Z4FvJLpGt0rg4WG2VihKDDJ7LuQY5vf0sYtnb+B7S6Q=; b=nufVc+6XF6YkO7IOval86Akhvmfa/HmbgNNoTXjKeM2kcRDuclJgASC0+IoTeIf5e5 gHesFYT2g00vMca0rjEsPWf84Eh+8vq52qT6ZawgKYhxqRskKIeu3GtiGs07iLL+ida0 k5eqBUUPo6r27ZJBLa84KPOqSlB/of+4vnDVp/K+QqD7dBTNJHGfBo7V0izijJNP6M5Q wd0hqaANZBt1oEnwAexNVh9jejxh+8wI4DE/0M0fqcmCMLO1ESimNg65RjqJj4EEXNWN DLRGFpcmhFhEsruB9mtj14fYRjVCUZdlbFiKQyO1r9NY6GaM7jVs3EK0JZNB5FW6lhvF hSyg== X-Forwarded-Encrypted: i=1; AJvYcCUzPpc3zwUe+oDFD7SLUbtHc+2sAnIScDvXO3bU+C0ON+ZgXZba6Sscqf7WONc3i6v/pctOmwlXrr8N6mNn@lists.linux.dev X-Gm-Message-State: AOJu0YzNkFlgG62od4hJgCAui3e2Aa+JmA2v8cnMjQHofElHg0ZWk6YS YtYQOVrRfk7O19zWZbu6SnckmVFrs6kBn8mbgBI0q9f/MJp1Tjr/LwZz X-Gm-Gg: AZuq6aJrDN45OLxyJY9H/6ns7M8emPxk75J/XQhd3dlStB9pWzHoCk2uQ8zdq+mqy29 9l8S4xZTMFqc419W5k0I1cfjZrtoBGLHHXCtWoWp1h7mimIP59G8EyOWgseqKQZ1hvokdym7y9f MbNz6LWYegY48IMBzj1K9z7Rr4XU9+xjh2TiPxjslEJ91C95hNisr9zo33HcwyfMa8/mSZ8mOBb j1+m4art94DDItY9QcHEdFuNaOdJFiQmKmlC2XknYcMSbR4C9S7cSHjvxPZtL21+rEQP67iyDA3 4NlLckXsYuF6NoTnluzEPPnk6pkgGW3LUr6dFT/sQO/Q/OOelJQnaSEtrlZeRlKIvzWhznfibjC ciuw/qQ10bIF15BE/iQqOBU02L0kiKjyqKbTgaeYo82P5Iz0yHHcuxdzB2ULtw8CZMVTBhY0zr1 TIJfoDDXHVfsKYJ1TYvHEVF/r/J3Vq1P965JBcLDB7cG6dwndjz1ccQqmGXebijBlRhYOemRHV2 jWoWRmOScg= X-Received: by 2002:a05:6000:1868:b0:429:c851:69ab with SMTP id ffacd0b85a97d-435f3ab2d43mr19870372f8f.55.1770119342363; Tue, 03 Feb 2026 03:49:02 -0800 (PST) Received: from localhost.localdomain ([31.206.212.157]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-435e13235f5sm48418880f8f.29.2026.02.03.03.49.01 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Tue, 03 Feb 2026 03:49:01 -0800 (PST) From: Baran Arda To: gregkh@linuxfoundation.org Cc: ovidiu.panait.oss@gmail.com, gshahrouzi@gmail.com, linux-staging@lists.linux.dev, linux-kernel@vger.kernel.org, baran9arda@gmail.com Subject: [PATCH v2] staging: axis-fifo: fix sleep while holding mutex Date: Tue, 3 Feb 2026 14:48:58 +0300 Message-Id: <20260203114858.28278-1-baran9arda@gmail.com> X-Mailer: git-send-email 2.39.5 (Apple Git-154) Precedence: bulk X-Mailing-List: linux-staging@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The driver calls wait_event_interruptible_timeout() while holding a mutex. This can lead to a deadlock or poor performance as the mutex is held while the process is sleeping, preventing other processes from accessing the device. This patch moves the wait_event call outside of the mutex lock in both read and write operations. Signed-off-by: Baran Arda --- drivers/staging/axis-fifo/axis-fifo.c | 30 +++++++++++++-------------- 1 file changed, 15 insertions(+), 15 deletions(-) diff --git a/drivers/staging/axis-fifo/axis-fifo.c b/drivers/staging/axis-fifo/axis-fifo.c index 509d620d6ce7..a651c59a80ea 100644 --- a/drivers/staging/axis-fifo/axis-fifo.c +++ b/drivers/staging/axis-fifo/axis-fifo.c @@ -197,11 +197,10 @@ static ssize_t axis_fifo_read(struct file *f, char __user *buf, goto end_unlock; } } else { - /* opened in blocking mode - * wait for a packet available interrupt (or timeout) - * if nothing is currently available + /* + * Opened in blocking mode. Wait for a packet available + * interrupt (or timeout) before acquiring the lock. */ - mutex_lock(&fifo->read_lock); ret = wait_event_interruptible_timeout(fifo->read_queue, ioread32(fifo->base_addr + XLLF_RDFO_OFFSET), read_timeout); @@ -214,8 +213,10 @@ static ssize_t axis_fifo_read(struct file *f, char __user *buf, ret); } - goto end_unlock; + return ret; } + + mutex_lock(&fifo->read_lock); } bytes_available = ioread32(fifo->base_addr + XLLF_RLR_OFFSET); @@ -340,27 +341,26 @@ static ssize_t axis_fifo_write(struct file *f, const char __user *buf, goto end_unlock; } } else { - /* opened in blocking mode */ - - /* wait for an interrupt (or timeout) if there isn't - * currently enough room in the fifo + /* + * Opened in blocking mode. Wait for enough room in the FIFO + * (or timeout) before acquiring the lock. */ - mutex_lock(&fifo->write_lock); ret = wait_event_interruptible_timeout(fifo->write_queue, ioread32(fifo->base_addr + XLLF_TDFV_OFFSET) - >= words_to_write, + >= words_to_write, write_timeout); if (ret <= 0) { - if (ret == 0) { + if (ret == 0) ret = -EAGAIN; - } else if (ret != -ERESTARTSYS) { + else if (ret != -ERESTARTSYS) dev_err(fifo->dt_device, "wait_event_interruptible_timeout() error in write (ret=%i)\n", ret); - } - goto end_unlock; + return ret; } + + mutex_lock(&fifo->write_lock); } txbuf = vmemdup_user(buf, len); -- 2.39.5 (Apple Git-154)