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fixed close race conditions in lwip_select (for LWIP_NETCONN_FULLDUPLEX)

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This commit is contained in:
goldsimon 2017-02-24 21:29:29 +01:00
parent f4d13d52d3
commit a38e937dd6
2 changed files with 77 additions and 4 deletions
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3
CHANGELOG
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@ -26,6 +26,9 @@ HISTORY
++ Bugfixes:
2017-02-24: Simon Goldschmidt
* sockets.c: fixed close race conditions in lwip_select (for LWIP_NETCONN_FULLDUPLEX)
2017-02-24: Simon Goldschmidt
* sockets.c: fixed that select ignored invalid/not open sockets in the fd_sets (bug #50392)

78
src/api/sockets.c
View File

@ -453,7 +453,7 @@ alloc_socket(struct netconn *newconn, int accepted)
for (i = 0; i < NUM_SOCKETS; ++i) {
/* Protect socket array */
SYS_ARCH_PROTECT(lev);
if (!sockets[i].conn && (sockets[i].select_waiting == 0)) {
if (!sockets[i].conn) {
#if LWIP_NETCONN_FULLDUPLEX
if (sockets[i].fd_used) {
continue;
@ -1420,7 +1420,7 @@ lwip_selscan(int maxfdp1, fd_set *readset_in, fd_set *writeset_in, fd_set *excep
}
/* First get the socket's status (protected)... */
SYS_ARCH_PROTECT(lev);
sock = tryget_socket(i);
sock = tryget_socket_unconn(i);
if (sock != NULL) {
void* lastdata = sock->lastdata;
s16_t rcvevent = sock->rcvevent;
@ -1463,6 +1463,68 @@ lwip_selscan(int maxfdp1, fd_set *readset_in, fd_set *writeset_in, fd_set *excep
return nready;
}
#if LWIP_NETCONN_FULLDUPLEX
/* Mark all of the set sockets in one of the three fdsets passed to select as used.
* All sockets are marked (and later unmarked), whether they are open or not.
* This is OK as lwip_selscan aborts select when non-open sockets are found.
*/
static void
lwip_select_inc_sockets_used_set(int maxfdp, fd_set *fdset, fd_set *used_sockets)
{
SYS_ARCH_DECL_PROTECT(lev);
if (fdset) {
int i;
for (i = LWIP_SOCKET_OFFSET; i < maxfdp; i++) {
/* if this FD is in the set, lock it (unless already done) */
if (FD_ISSET(i, fdset) && !FD_ISSET(i, used_sockets)) {
struct lwip_sock *sock;
SYS_ARCH_PROTECT(lev);
sock = tryget_socket_unconn(i);
if (sock != NULL) {
sock_inc_used(sock);
FD_SET(i, used_sockets);
}
SYS_ARCH_UNPROTECT(lev);
}
}
}
}
/* Mark all sockets passed to select as used to prevent them from being freed
* from other threads while select is running.
* Marked sockets are added to 'used_sockets' to mark them only once an be able
* to unmark them correctly.
*/
static void
lwip_select_inc_sockets_used(int maxfdp, fd_set *fdset1, fd_set *fdset2, fd_set *fdset3, fd_set *used_sockets)
{
FD_ZERO(used_sockets);
lwip_select_inc_sockets_used_set(maxfdp, fdset1, used_sockets);
lwip_select_inc_sockets_used_set(maxfdp, fdset2, used_sockets);
lwip_select_inc_sockets_used_set(maxfdp, fdset3, used_sockets);
}
/* Let go all sockets that were marked as used when starting select */
static void
lwip_select_dec_sockets_used(int maxfdp, fd_set *used_sockets)
{
int i;
for (i = LWIP_SOCKET_OFFSET; i < maxfdp; i++) {
/* if this FD is not in the set, continue */
if (FD_ISSET(i, used_sockets)) {
struct lwip_sock *sock = tryget_socket_unconn(i);
LWIP_ASSERT("socket gone at the end of select", sock != NULL);
if (sock != NULL) {
done_socket(sock);
}
}
}
}
#else /* LWIP_NETCONN_FULLDUPLEX */
#define lwip_select_inc_sockets_used(maxfdp1, readset, writeset, exceptset, used_sockets)
#define lwip_select_dec_sockets_used(maxfdp1, used_sockets)
#endif /* LWIP_NETCONN_FULLDUPLEX */
int
lwip_select(int maxfdp1, fd_set *readset, fd_set *writeset, fd_set *exceptset,
struct timeval *timeout)
@ -1476,6 +1538,9 @@ lwip_select(int maxfdp1, fd_set *readset, fd_set *writeset, fd_set *exceptset,
int maxfdp2;
#if LWIP_NETCONN_SEM_PER_THREAD
int waited = 0;
#endif
#if LWIP_NETCONN_FULLDUPLEX
fd_set used_sockets;
#endif
SYS_ARCH_DECL_PROTECT(lev);
@ -1489,6 +1554,8 @@ lwip_select(int maxfdp1, fd_set *readset, fd_set *writeset, fd_set *exceptset,
return -1;
}
lwip_select_inc_sockets_used(maxfdp1, readset, writeset, exceptset, &used_sockets);
/* Go through each socket in each list to count number of sockets which
currently match */
nready = lwip_selscan(maxfdp1, readset, writeset, exceptset, &lreadset, &lwriteset, &lexceptset);
@ -1524,6 +1591,7 @@ lwip_select(int maxfdp1, fd_set *readset, fd_set *writeset, fd_set *exceptset,
if (sys_sem_new(&select_cb.sem, 0) != ERR_OK) {
/* failed to create semaphore */
set_errno(ENOMEM);
lwip_select_dec_sockets_used(maxfdp1, &used_sockets);
return -1;
}
#endif /* LWIP_NETCONN_SEM_PER_THREAD */
@ -1551,7 +1619,7 @@ lwip_select(int maxfdp1, fd_set *readset, fd_set *writeset, fd_set *exceptset,
(exceptset && FD_ISSET(i, exceptset))) {
struct lwip_sock *sock;
SYS_ARCH_PROTECT(lev);
sock = tryget_socket(i);
sock = tryget_socket_unconn(i);
if (sock != NULL) {
sock->select_waiting++;
LWIP_ASSERT("sock->select_waiting > 0", sock->select_waiting > 0);
@ -1598,7 +1666,7 @@ lwip_select(int maxfdp1, fd_set *readset, fd_set *writeset, fd_set *exceptset,
(exceptset && FD_ISSET(i, exceptset))) {
struct lwip_sock *sock;
SYS_ARCH_PROTECT(lev);
sock = tryget_socket(i);
sock = tryget_socket_unconn(i);
if (sock != NULL) {
/* for now, handle select_waiting==0... */
LWIP_ASSERT("sock->select_waiting > 0", sock->select_waiting > 0);
@ -1641,6 +1709,7 @@ lwip_select(int maxfdp1, fd_set *readset, fd_set *writeset, fd_set *exceptset,
if (nready < 0) {
/* This happens when a socket got closed while waiting */
set_errno(EBADF);
lwip_select_dec_sockets_used(maxfdp1, &used_sockets);
return -1;
}
@ -1658,6 +1727,7 @@ lwip_select(int maxfdp1, fd_set *readset, fd_set *writeset, fd_set *exceptset,
LWIP_DEBUGF(SOCKETS_DEBUG, ("lwip_select: nready=%d\n", nready));
return_copy_fdsets:
lwip_select_dec_sockets_used(maxfdp1, &used_sockets);
set_errno(0);
if (readset) {
*readset = lreadset;