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net/netdev: Add an algorithm to prevent an interface index from being reused until all network interfaces have by assigned once. The prevents removable devices from being removed, unregistered and re-installed, re-registered and keeping the same interface index.

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This commit is contained in:
Gregory Nutt 2018-06-25 12:57:42 -06:00
parent c65e1aa3df
commit 5a0cf3c9a8
3 changed files with 47 additions and 18 deletions
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8
net/netdev/netdev.h
View File

@ -89,6 +89,14 @@ EXTERN struct net_driver_s *g_netdevices;
*/
EXTERN uint32_t g_devset;
/* The set of network devices that have been freed. The purpose of this
* set is to postpone reuse of a interface index for as long as possible,
* i.e., don't reuse an interface index until all of the possible indices
* have been used.
*/
EXTERN uint32_t g_devfreed;
#endif
/****************************************************************************

52
net/netdev/netdev_register.c
View File

@ -104,6 +104,14 @@ struct net_driver_s *g_netdevices = NULL;
*/
uint32_t g_devset;
/* The set of network devices that have been freed. The purpose of this
* set is to postpone reuse of a interface index for as long as possible,
* i.e., don't reuse an interface index until all of the possible indices
* have been used.
*/
uint32_t g_devfreed;
#endif
/****************************************************************************
@ -175,29 +183,41 @@ static int find_devnum(FAR const char *devfmt)
#ifdef CONFIG_NETDEV_IFINDEX
static int get_ifindex(void)
{
uint32_t devset;
int ndx;
/* Search for an unused index */
/* Try to postpone re-using interface indices as long as possible */
for (ndx = 0; ndx < MAX_IFINDEX; ndx++)
{
uint32_t bit = 1L << ndx;
if ((g_devset & bit) == 0)
{
/* Indicate that this index is in use */
devset = g_devset | g_devfreed;
if (devset == 0xffffffff)
{
/* Time start re-using interface indices */
g_devset |= bit;
devset = g_devset;
g_devfreed = 0;
}
/* NOTE that the index + 1 is returned. Zero is reserved to
* mean no-index in the POSIX standards.
*/
/* Search for an unused index */
net_unlock();
return ndx + 1;
}
}
for (ndx = 0; ndx < MAX_IFINDEX; ndx++)
{
uint32_t bit = 1L << ndx;
if ((devset & bit) == 0)
{
/* Indicate that this index is in use */
return -ENOSPC;
g_devset |= bit;
/* NOTE that the index + 1 is returned. Zero is reserved to
* mean no-index in the POSIX standards.
*/
net_unlock();
return ndx + 1;
}
}
return -ENOSPC;
}
#endif

5
net/netdev/netdev_unregister.c
View File

@ -97,8 +97,9 @@ static inline void free_ifindex(int ndx)
/* The bit should be in the set state */
DEBUGASSERT((g_devset & bit) != 0);
g_devset &= ~bit;
DEBUGASSERT((g_devset & bit) != 0 && (g_devfreed & bit) == 0);
g_devset &= ~bit;
g_devfreed |= bit;
}
#endif