From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.ozlabs.org (gandalf.ozlabs.org [150.107.74.76]) (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 720A94A1399; Thu, 24 Sep 2026 15:22:31 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=150.107.74.76 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790263357; cv=none; b=pT9fIEEKN3lkDpgpxG+oRRQFBLCDOXxHXcfO4hPoXPI9kWAGwPwmU+N44Wndtr5/XFYpdJMW6ZDVhnde3TvrrbnaPFE1Gs8CimR/HeIsqTquF3r7nBTMNoQBBjTQS/qIdv3hPo+/HkpCarcmwoBBkrMrzycvC+Xsjju2R8tsSX0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790263357; c=relaxed/simple; bh=2n1BvkR9DETXilpqL0zMLDeUUZ8rDSPtEh2hDRJHDHc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=MUyTcyTn7qWqp+GnRZwEwexcAO5CW8CvFDhDgQ2X9cWKwvuCl8hig35+HpFWEA9Rc1R9GN/3V6Tp0K6T0ZjDF6zlOinW/PQEvIwSKsXLmR+4RhvPkKEFejDt49Tx/pc8GQvKA8GfKAyQtrzFNUf7XApIMQ3HuE2IQgwk869tjV8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=ozlabs.org; spf=pass smtp.mailfrom=ozlabs.org; dkim=pass (2048-bit key) header.d=ozlabs.org header.i=@ozlabs.org header.b=mL2cerB+; arc=none smtp.client-ip=150.107.74.76 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=ozlabs.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=ozlabs.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=ozlabs.org header.i=@ozlabs.org header.b="mL2cerB+" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ozlabs.org; s=201707; t=1790263324; bh=fehRqJAWhTjTPbm31hNCNZ8otyaWkpo7uCYKj32njIE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=mL2cerB+t8EvkTpqPM1fQgeOvOpMVpmxSepHZW9RSWeJaHGIj8jYwNmAPv0aGJ28r 2mnhGxSas4GTVJJU2rg63dj5qlHf3j5GvGNgfSx8CsnB5UHUladtWSH0rQZJannV6F 597yPUM159LLo6wYObfAtU+EIpGe/qMwABslCbznB+F4BbcmoJOCCHjrQ+LrJk6Q+U 1yvQPs7qAtkYdpXXMj58tatCj1HkPceUnMfdybHFIUIP8/gu6YjC6qC4BYG4719lA5 mMoNYJNmyPaWM9+EYXH+MiT1dIy2StKgsmqnJnl6uk5r5bmBC2wcn4qIBCzubdCaK3 EIiNMoUTI0bdA== Received: from authenticated.ozlabs.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange x25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by mail.ozlabs.org (Postfix) with ESMTPSA id 4hrHcq3K4gz4wHr; Fri, 25 Sep 2026 01:22:03 +1000 (AEST) From: Matt Evans To: Alex Williamson , Leon Romanovsky , Jason Gunthorpe , Alex Mastro , =?UTF-8?q?Christian=20K=C3=B6nig?= , Bjorn Helgaas , Logan Gunthorpe , Kevin Tian , Pranjal Shrivastava , Longfang Liu Cc: Mahmoud Adam , David Matlack , =?UTF-8?q?Bj=C3=B6rn=20T=C3=B6pel?= , Sumit Semwal , Ankit Agrawal , Alistair Popple , Vivek Kasireddy , linux-kernel@vger.kernel.org, linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, kvm@vger.kernel.org, linux-pci@vger.kernel.org Subject: [PATCH v7 3/9] dma-buf: Provide dma_buf_set_name() Date: Thu, 24 Sep 2026 16:21:46 +0100 Message-ID: <20260924152159.49702-4-matt@ozlabs.org> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20260924152159.49702-1-matt@ozlabs.org> References: <20260924152159.49702-1-matt@ozlabs.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Allow exporters to set the name of buffers, during export or for subsequent updates. This is useful to express buffer-specific debug information, indicate state particular to the exporter's usage, etc. Only exporters and userspace are expected to set names; it isn't sensible for importers to do it. Originally, the static dma_buf_set_name() was used for DMA_BUF_SET_NAME ioctls, taking a __user string parameter. Export this function as a generic set-name helper, taking a kernel-allocated string. The SET_NAME ioctls now locally duplicate the __user string, and use the new function to set the name. Signed-off-by: Matt Evans --- drivers/dma-buf/dma-buf.c | 78 ++++++++++++++++++++++++--------------- include/linux/dma-buf.h | 2 + 2 files changed, 50 insertions(+), 30 deletions(-) diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c index 4c9add51f9ef..e4ec504e9288 100644 --- a/drivers/dma-buf/dma-buf.c +++ b/drivers/dma-buf/dma-buf.c @@ -404,34 +404,6 @@ static __poll_t dma_buf_poll(struct file *file, poll_table *poll) return events; } -/** - * dma_buf_set_name - Set a name to a specific dma_buf to track the usage. - * It could support changing the name of the dma-buf if the same - * piece of memory is used for multiple purpose between different devices. - * - * @dmabuf: [in] dmabuf buffer that will be renamed. - * @buf: [in] A piece of userspace memory that contains the name of - * the dma-buf. - * - * Returns 0 on success. If the dma-buf buffer is already attached to - * devices, return -EBUSY. - * - */ -static long dma_buf_set_name(struct dma_buf *dmabuf, const char __user *buf) -{ - char *name = strndup_user(buf, DMA_BUF_NAME_LEN); - - if (IS_ERR(name)) - return PTR_ERR(name); - - spin_lock(&dmabuf->name_lock); - kfree(dmabuf->name); - dmabuf->name = name; - spin_unlock(&dmabuf->name_lock); - - return 0; -} - #if IS_ENABLED(CONFIG_SYNC_FILE) static long dma_buf_export_sync_file(struct dma_buf *dmabuf, void __user *user_data) @@ -577,8 +549,19 @@ static long dma_buf_ioctl(struct file *file, return ret; case DMA_BUF_SET_NAME_A: - case DMA_BUF_SET_NAME_B: - return dma_buf_set_name(dmabuf, (const char __user *)arg); + case DMA_BUF_SET_NAME_B: { + char *name = strndup_user((const char __user *)arg, + DMA_BUF_NAME_LEN); + + if (IS_ERR(name)) + return PTR_ERR(name); + + ret = dma_buf_set_name(dmabuf, name); + if (ret) + kfree(name); + + return ret; + } #if IS_ENABLED(CONFIG_SYNC_FILE) case DMA_BUF_IOCTL_EXPORT_SYNC_FILE: @@ -874,6 +857,41 @@ void dma_buf_put(struct dma_buf *dmabuf) } EXPORT_SYMBOL_NS_GPL(dma_buf_put, "DMA_BUF"); +/** + * dma_buf_set_name - Set a dmabuf's name + * Intended to be used by the exporter to set a name for debug + * purposes. This can also change an existing name if the same piece + * of memory is used for multiple purposes over time. + * + * @dmabuf: [in] dmabuf buffer that will be renamed. + * @name: [in] The name of the dma-buf, allocated with kmalloc() or + * similar. This takes ownership of the allocation + * on success, which will be kfree()d when the + * dmabuf is released or a new name assigned. + * + * Returns 0 on success, -EINVAL if the name is NULL, or -E2BIG if the + * name (including terminator) exceeds DMA_BUF_NAME_LEN. + */ +int dma_buf_set_name(struct dma_buf *dmabuf, char *name) +{ + if (!name) + return -EINVAL; + + /* dmabuffs_dname() won't use the string if the length + * (including terminator) exceeds DMA_BUF_NAME_LEN: + */ + if (strlen(name) >= DMA_BUF_NAME_LEN) + return -E2BIG; + + spin_lock(&dmabuf->name_lock); + kfree(dmabuf->name); + dmabuf->name = name; + spin_unlock(&dmabuf->name_lock); + + return 0; +} +EXPORT_SYMBOL_NS_GPL(dma_buf_set_name, "DMA_BUF"); + static int dma_buf_wrap_sg_table(struct sg_table **sg_table) { struct scatterlist *to_sg, *from_sg; diff --git a/include/linux/dma-buf.h b/include/linux/dma-buf.h index d15b2b31d3c9..952a2c196ad4 100644 --- a/include/linux/dma-buf.h +++ b/include/linux/dma-buf.h @@ -571,6 +571,8 @@ void dma_buf_fd_install(struct dma_buf *dmabuf, int fd); struct dma_buf *dma_buf_get(int fd); void dma_buf_put(struct dma_buf *dmabuf); +int dma_buf_set_name(struct dma_buf *dmabuf, char *name); + struct sg_table *dma_buf_map_attachment(struct dma_buf_attachment *, enum dma_data_direction); void dma_buf_unmap_attachment(struct dma_buf_attachment *, struct sg_table *, -- 2.50.1 (Apple Git-155)