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Message-ID: <s5mhlz5szowwse52t6u44u3despluqb2ucudmmolx55vmtvs2l@eptqoed2qwmv>
Date: Mon, 28 Oct 2024 14:44:53 +0100
From: Stefano Garzarella <sgarzare@...hat.com>
To: Konstantin Shkolnyy <kshk@...ux.ibm.com>
Cc: virtualization@...ts.linux.dev, netdev@...r.kernel.org,
linux-kernel@...r.kernel.org, mjrosato@...ux.ibm.com
Subject: Re: [PATCH v3] vsock/test: fix failures due to wrong SO_RCVLOWAT
parameter
On Fri, Oct 25, 2024 at 10:41:24AM -0500, Konstantin Shkolnyy wrote:
>This happens on 64-bit big-endian machines.
>SO_RCVLOWAT requires an int parameter. However, instead of int, the test
>uses unsigned long in one place and size_t in another. Both are 8 bytes
>long on 64-bit machines. The kernel, having received the 8 bytes, doesn't
>test for the exact size of the parameter, it only cares that it's >=
>sizeof(int), and casts the 4 lower-addressed bytes to an int, which, on
>a big-endian machine, contains 0. 0 doesn't trigger an error, SO_RCVLOWAT
>returns with success and the socket stays with the default SO_RCVLOWAT = 1,
>which results in vsock_test failures, while vsock_perf doesn't even notice
>that it's failed to change it.
>
>Fixes: b1346338fbae ("vsock_test: POLLIN + SO_RCVLOWAT test")
>Fixes: 542e893fbadc ("vsock/test: two tests to check credit update logic")
>Fixes: 8abbffd27ced ("test/vsock: vsock_perf utility")
>Signed-off-by: Konstantin Shkolnyy <kshk@...ux.ibm.com>
>---
>
>Notes:
> The problem was found on s390 (big endian), while x86-64 didn't show it. After this fix, all tests pass on s390.
>Changes for v3:
>- fix the same problem in vsock_perf and update commit message
>Changes for v2:
>- add "Fixes:" lines to the commit message
Reviewed-by: Stefano Garzarella <sgarzare@...hat.com>
>
> tools/testing/vsock/vsock_perf.c | 6 +++---
> tools/testing/vsock/vsock_test.c | 4 ++--
> 2 files changed, 5 insertions(+), 5 deletions(-)
>
>diff --git a/tools/testing/vsock/vsock_perf.c b/tools/testing/vsock/vsock_perf.c
>index 4e8578f815e0..22633c2848cc 100644
>--- a/tools/testing/vsock/vsock_perf.c
>+++ b/tools/testing/vsock/vsock_perf.c
>@@ -133,7 +133,7 @@ static float get_gbps(unsigned long bits, time_t ns_delta)
> ((float)ns_delta / NSEC_PER_SEC);
> }
>
>-static void run_receiver(unsigned long rcvlowat_bytes)
>+static void run_receiver(int rcvlowat_bytes)
> {
> unsigned int read_cnt;
> time_t rx_begin_ns;
>@@ -163,7 +163,7 @@ static void run_receiver(unsigned long rcvlowat_bytes)
> printf("Listen port %u\n", port);
> printf("RX buffer %lu bytes\n", buf_size_bytes);
> printf("vsock buffer %lu bytes\n", vsock_buf_bytes);
>- printf("SO_RCVLOWAT %lu bytes\n", rcvlowat_bytes);
>+ printf("SO_RCVLOWAT %d bytes\n", rcvlowat_bytes);
>
> fd = socket(AF_VSOCK, SOCK_STREAM, 0);
>
>@@ -439,7 +439,7 @@ static long strtolx(const char *arg)
> int main(int argc, char **argv)
> {
> unsigned long to_send_bytes = DEFAULT_TO_SEND_BYTES;
>- unsigned long rcvlowat_bytes = DEFAULT_RCVLOWAT_BYTES;
>+ int rcvlowat_bytes = DEFAULT_RCVLOWAT_BYTES;
> int peer_cid = -1;
> bool sender = false;
>
>diff --git a/tools/testing/vsock/vsock_test.c b/tools/testing/vsock/vsock_test.c
>index f851f8961247..30857dd4ca97 100644
>--- a/tools/testing/vsock/vsock_test.c
>+++ b/tools/testing/vsock/vsock_test.c
>@@ -833,7 +833,7 @@ static void test_stream_poll_rcvlowat_server(const struct test_opts *opts)
>
> static void test_stream_poll_rcvlowat_client(const struct test_opts *opts)
> {
>- unsigned long lowat_val = RCVLOWAT_BUF_SIZE;
>+ int lowat_val = RCVLOWAT_BUF_SIZE;
> char buf[RCVLOWAT_BUF_SIZE];
> struct pollfd fds;
> short poll_flags;
>@@ -1282,7 +1282,7 @@ static void test_stream_rcvlowat_def_cred_upd_client(const struct test_opts *opt
> static void test_stream_credit_update_test(const struct test_opts *opts,
> bool low_rx_bytes_test)
> {
>- size_t recv_buf_size;
>+ int recv_buf_size;
> struct pollfd fds;
> size_t buf_size;
> void *buf;
>--
>2.34.1
>
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