From: "T.J. Mercier" <tjmercier@google.com>
To: kraxel@redhat.com, vivek.kasireddy@intel.com,
Shuah Khan <shuah@kernel.org>,
Andrew Lunn <andrew+netdev@lunn.ch>,
"David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Jakub Kicinski <kuba@kernel.org>,
Paolo Abeni <pabeni@redhat.com>
Cc: "T.J. Mercier" <tjmercier@google.com>,
linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org,
netdev@vger.kernel.org, bpf@vger.kernel.org
Subject: [PATCH] selftests: Open /dev/udmabuf O_RDONLY
Date: Thu, 25 Jun 2026 11:15:55 -0700 [thread overview]
Message-ID: <20260625181557.1086105-1-tjmercier@google.com> (raw)
Write permissions on the /dev/udmabuf device file are not required to
issue ioctls and allocate udmabufs. Applications should be opening this
file as O_RDONLY. The BPF dmabuf_iter selftest already does this. [1]
Remove the write access mode from the drivers/dma-buf/udmabuf.c and
drivers/net/hw/ncdevmem.c selftests.
[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/tools/testing/selftests/bpf/prog_tests/dmabuf_iter.c?h=v7.1#n49
Signed-off-by: T.J. Mercier <tjmercier@google.com>
---
tools/testing/selftests/drivers/dma-buf/udmabuf.c | 2 +-
tools/testing/selftests/drivers/net/hw/ncdevmem.c | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/tools/testing/selftests/drivers/dma-buf/udmabuf.c b/tools/testing/selftests/drivers/dma-buf/udmabuf.c
index d78aec662586..ced0b95c876c 100644
--- a/tools/testing/selftests/drivers/dma-buf/udmabuf.c
+++ b/tools/testing/selftests/drivers/dma-buf/udmabuf.c
@@ -140,7 +140,7 @@ int main(int argc, char *argv[])
ksft_print_header();
ksft_set_plan(7);
- devfd = open("/dev/udmabuf", O_RDWR);
+ devfd = open("/dev/udmabuf", O_RDONLY);
if (devfd < 0) {
ksft_print_msg(
"%s: [skip,no-udmabuf: Unable to access DMA buffer device file]\n",
diff --git a/tools/testing/selftests/drivers/net/hw/ncdevmem.c b/tools/testing/selftests/drivers/net/hw/ncdevmem.c
index e098d6534c3c..8114a29692fd 100644
--- a/tools/testing/selftests/drivers/net/hw/ncdevmem.c
+++ b/tools/testing/selftests/drivers/net/hw/ncdevmem.c
@@ -149,7 +149,7 @@ static struct memory_buffer *udmabuf_alloc(size_t size)
ctx->size = size;
- ctx->devfd = open("/dev/udmabuf", O_RDWR);
+ ctx->devfd = open("/dev/udmabuf", O_RDONLY);
if (ctx->devfd < 0) {
pr_err("[skip,no-udmabuf: Unable to access DMA buffer device file]");
goto err_free_ctx;
--
2.55.0.rc0.799.gd6f94ed593-goog
reply other threads:[~2026-06-25 18:16 UTC|newest]
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