[RFC 6/6] net/hinic: fix mutexes for multi-process

[Stephen Hemminger <stephen@networkplumber.org>]

The hinic driver supports secondary processes, as shown by the
explicit check in hinic_dev_init(). Multiple mutexes are located
in structures allocated in shared memory (dev_private and
rte_zmalloc'd structures) that are accessible by both primary
and secondary processes.

However, the mutexes are initialized without PTHREAD_PROCESS_SHARED
attribute, which means synchronization between processes is
undefined behavior.

POSIX mutexes are by default private to the process creating them.
When a mutex protects data structures in shared memory that are
accessed by multiple processes, pthread_mutexattr_setpshared() must
be called with PTHREAD_PROCESS_SHARED.

Fix the hinic_mutex_init() wrapper function to set the
PTHREAD_PROCESS_SHARED attribute on all mutexes.

Bugzilla ID: 662
Fixes: ae865766b334 ("net/hinic: replace spinlock with mutex")
Cc: stable@dpdk.org

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
---
 drivers/net/hinic/base/hinic_compat.h | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/net/hinic/base/hinic_compat.h b/drivers/net/hinic/base/hinic_compat.h
index d3994c50e9..18148a119e 100644
--- a/drivers/net/hinic/base/hinic_compat.h
+++ b/drivers/net/hinic/base/hinic_compat.h
@@ -197,10 +197,21 @@ static inline u16 ilog2(u32 n)
 	return res;
 }
 
+/*
+ * Initialize mutex for process-shared access.
+ * Structures may be in shared memory accessible by multiple processes,
+ * so mutexes must use PTHREAD_PROCESS_SHARED.
+ */
 static inline int hinic_mutex_init(pthread_mutex_t *pthreadmutex,
 					const pthread_mutexattr_t *mattr)
 {
-	return pthread_mutex_init(pthreadmutex, mattr);
+	pthread_mutexattr_t attr;
+
+	pthread_mutexattr_init(&attr);
+	pthread_mutexattr_setpshared(&attr, PTHREAD_PROCESS_SHARED);
+	pthread_mutex_init(pthreadmutex, mattr ? mattr : &attr);
+	pthread_mutexattr_destroy(&attr);
+	return 0;
 }
 
 static inline int hinic_mutex_destroy(pthread_mutex_t *pthreadmutex)
-- 
2.51.0