From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id F03A837A825; Wed, 30 Sep 2026 18:02:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790791339; cv=none; b=erBxYYCRVIYbEQG/h+cGS2AUrCimV63WYZPq3RCliThdJjcsDdhbPryWJ1wtUDoZN0sWDGX0BxADX/Bb/A7r52A1q3KFAz4lQxnmqkMAj6b5swjPxtTtxwZeVK4h8Z+lyMfJXJaQyl21Vdukz8ceOJjAT2nuIALHKsBQK+mwg7I= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790791339; c=relaxed/simple; bh=iHwWiZdOm32OQveBT8UdPzKtV/pLqQadxT2h0wFaUEM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=YQXSi5qibCBtOMl7UjrchZWalFq2L5aJYQbyBtadbNAxksN1TYRcT5d86MCblbFIP7+4zNHV9YP9g1jhuRCkZh9j8elmTVRInoF3kuYsQsUgzqTPkkb4bPxkIkcRSsjprdvT4/9Kusv8rht8hkJX5D4mxHmksgXFBAmm2WaHLmM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=k6dRe4Kk; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="k6dRe4Kk" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 577E51F000FF; Wed, 30 Sep 2026 18:02:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1790791337; bh=RFwy+I9utRx8t7Jknv8f1ApUXdK/HMAf4+x2AHQzN70=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=k6dRe4KkdjvHD4wa7srtN1qK6qUrcufUxDP13dBW6OUU3WityZCeQTvm30N0VsiFx Ws6IBE4MwUOIGws7C8K9dRK+b+Tf1g7qS9Thrqw7H/DdXp2sIf/ywm7SEIyqw4j0TO 5gpuiZglGItl9pr1DdCQREhAVrEqaDMCKdHWFti0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Hui Su , Nam Cao , Sasha Levin Subject: [PATCH 5.15 265/752] staging: fbtft: make dirty_lock IRQ-safe Date: Wed, 30 Sep 2026 17:22:15 +0200 Message-ID: <20260930152404.015012477@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260930152358.131179731@linuxfoundation.org> References: <20260930152358.131179731@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Hui Su [ Upstream commit f576944a59f31bcffff121117ebf452c5dd162b7 ] fbtft_mkdirty() can be reached from the fbcon rendering path while processing printk() in hardirq context. Meanwhile, dirty_lock is also taken by fbtft_deferred_io() in workqueue context with local interrupts enabled. Lockdep reports a possible IRQ lock inversion involving dirty_lock and console_owner. A hardirq can interrupt a CPU holding dirty_lock and enter the console rendering path, which can attempt to acquire dirty_lock again. The following lockdep report was observed on an RK3566 system with CONFIG_PROVE_LOCKING enabled: WARNING: possible irq lock inversion dependency detected swapper/2/0 just changed the state of lock: (console_owner){-...}-{0:0} but this lock took another, HARDIRQ-unsafe lock in the past: (&par->dirty_lock){+.+.}-{2:2} CPU0 CPU1 ---- ---- lock(&par->dirty_lock); local_irq_disable(); lock(console_owner); lock(&par->dirty_lock); lock(console_owner); *** DEADLOCK *** Use spin_lock_irqsave() for fbtft_mkdirty() and spin_lock_irq() for fbtft_deferred_io(). They only access the dirty line range, so the IRQ-off regions remain short. Fixes: c296d5f9957c ("staging: fbtft: core support") Signed-off-by: Hui Su Link: https://lore.kernel.org/lkml/20260804173712.176017-1-sh_def@163.com/ Reviewed-by: Nam Cao Link: https://patch.msgid.link/20260807150953.2811933-3-sh_def@163.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin --- drivers/staging/fbtft/fbtft-core.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/drivers/staging/fbtft/fbtft-core.c b/drivers/staging/fbtft/fbtft-core.c index 67604a4d9a39f..8d7d135835ed4 100644 --- a/drivers/staging/fbtft/fbtft-core.c +++ b/drivers/staging/fbtft/fbtft-core.c @@ -303,6 +303,7 @@ static void fbtft_mkdirty(struct fb_info *info, int y, int height) { struct fbtft_par *par = info->par; struct fb_deferred_io *fbdefio = info->fbdefio; + unsigned long flags; /* special case, needed ? */ if (y == -1) { @@ -311,12 +312,12 @@ static void fbtft_mkdirty(struct fb_info *info, int y, int height) } /* Mark display lines/area as dirty */ - spin_lock(&par->dirty_lock); + spin_lock_irqsave(&par->dirty_lock, flags); if (y < par->dirty_lines_start) par->dirty_lines_start = y; if (y + height - 1 > par->dirty_lines_end) par->dirty_lines_end = y + height - 1; - spin_unlock(&par->dirty_lock); + spin_unlock_irqrestore(&par->dirty_lock, flags); /* Schedule deferred_io to update display (no-op if already on queue)*/ schedule_delayed_work(&info->deferred_work, fbdefio->delay); @@ -331,13 +332,13 @@ static void fbtft_deferred_io(struct fb_info *info, struct list_head *pagereflis unsigned int y_low = 0, y_high = 0; int count = 0; - spin_lock(&par->dirty_lock); + spin_lock_irq(&par->dirty_lock); dirty_lines_start = par->dirty_lines_start; dirty_lines_end = par->dirty_lines_end; /* set display line markers as clean */ par->dirty_lines_start = par->info->var.yres - 1; par->dirty_lines_end = 0; - spin_unlock(&par->dirty_lock); + spin_unlock_irq(&par->dirty_lock); /* Mark display lines as dirty */ list_for_each_entry(pageref, pagereflist, list) { -- 2.53.0