On Thu, 21 May 2020 17:11:12 -0700
Tasnim Bashar <tbas...@mellanox.com> wrote:
> Casting thread ID to handle is not accurate way to get thread handle.
> Need to use OpenThread function to get thread handle from thread ID.
>
> pthread_setaffinity_np and pthread_getaffinity_np functions
> for Windows are affected because of it.
Good catch.
Side note:
The sooner we move to a mature third-party pthread implementation, the better.
>
> Signed-off-by: Tasnim Bashar <tbas...@mellanox.com>
> ---
> lib/librte_eal/windows/include/pthread.h | 40 +++++++++++++++++++++---
> 1 file changed, 35 insertions(+), 5 deletions(-)
>
> diff --git a/lib/librte_eal/windows/include/pthread.h
> b/lib/librte_eal/windows/include/pthread.h
> index 0bbed5c3b8..d2a986f8fd 100644
> --- a/lib/librte_eal/windows/include/pthread.h
> +++ b/lib/librte_eal/windows/include/pthread.h
> @@ -18,6 +18,7 @@ extern "C" {
>
> #include <windows.h>
> #include <rte_common.h>
> +#include <rte_windows.h>
Build fails, because <rte_windows.h> doesn't include <rte_log.h>, macros from
which it uses. I'd rather include it there, so that <rte_windows.h> could be
used independently, but you can also add an include here.
If you include <rte_windows.h>, you don't need <windows.h> anymore.
>
> #define PTHREAD_BARRIER_SERIAL_THREAD TRUE
>
> @@ -50,7 +51,19 @@ typedef SYNCHRONIZATION_BARRIER pthread_barrier_t;
> static inline int
> eal_set_thread_affinity_mask(pthread_t threadid, unsigned long *cpuset)
> {
> - SetThreadAffinityMask((HANDLE) threadid, *cpuset);
> + HANDLE thread_handle = OpenThread(THREAD_ALL_ACCESS, FALSE, threadid);
> + if (thread_handle == NULL) {
> + RTE_LOG_WIN32_ERR("OpenThread()");
> + return -1;
> + }
> +
> + DWORD ret = SetThreadAffinityMask(thread_handle, *cpuset);
GetThreadAffinityMask() and SetThreadAffinityMask() operate on DWORD_PTR (8
bytes), not DWORD (4 byte). This applies to all usages of these functions in
the file and also to the type of "cpuset" parameter: it should be either "long
long *" (as rte_cpuset_t is declared) or just "rte_cpuset_t *".
Also, DPDK coding style suggests declaring variables at the start of the block
(i.e. function here and below).
> + if (ret == 0) {
> + RTE_LOG_WIN32_ERR("SetThreadAffinityMask()");
> + CloseHandle(thread_handle);
> + return -1;
> + }
> + CloseHandle(thread_handle);
> return 0;
> }
>
> @@ -60,12 +73,29 @@ eal_get_thread_affinity_mask(pthread_t threadid, unsigned
> long *cpuset)
> /* Workaround for the lack of a GetThreadAffinityMask()
> *API in Windows
> */
> - /* obtain previous mask by setting dummy mask */
> - DWORD dwprevaffinitymask =
> - SetThreadAffinityMask((HANDLE) threadid, 0x1);
Loss of data for the reason described above: here a 64-bit mask is
stored in a 32-bit variable, so later the wrong value of affinity will be
restored for cores 32 and on.
> + HANDLE thread_handle = OpenThread(THREAD_ALL_ACCESS, FALSE, threadid);
> + if (thread_handle == NULL) {
> + RTE_LOG_WIN32_ERR("OpenThread()");
> + return -1;
> + }
> +
> + /* obtain previous mask by setting dummy mask */
> + DWORD dwprevaffinitymask = SetThreadAffinityMask(thread_handle, 0x1);
> + if (dwprevaffinitymask == 0) {
> + RTE_LOG_WIN32_ERR("SetThreadAffinityMask()");
> + CloseHandle(thread_handle);
> + return -1;
> + }
> +
> /* set it back! */
> - SetThreadAffinityMask((HANDLE) threadid, dwprevaffinitymask);
> + DWORD ret = SetThreadAffinityMask(thread_handle, dwprevaffinitymask);
> + if (ret == 0) {
> + RTE_LOG_WIN32_ERR("SetThreadAffinityMask()");
> + CloseHandle(thread_handle);
> + return -1;
> + }
> *cpuset = dwprevaffinitymask;
> + CloseHandle(thread_handle);
> return 0;
> }
>
--
Dmitry Kozlyuk
