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Implement an utility function that can be used by device drivers to

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implement the ATMIOCGVCCS ioctls. This routine handles changing
VCC tables (which can occure because we cannot hold the driver mutex
while allocating memory) with a loop and a re-allocation, should the
table not fit in the allocated memory.
This commit is contained in:
Hartmut Brandt 2003-07-15 10:37:09 +00:00
parent 198b0c39a9
commit 09d405d969
2 changed files with 59 additions and 0 deletions
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2
sys/net/if_atm.h
View file

@ -268,4 +268,6 @@ void atm_input(struct ifnet *, struct atm_pseudohdr *,
struct mbuf *, void *);
int atm_output(struct ifnet *, struct mbuf *, struct sockaddr *,
struct rtentry *);
struct atmio_vcctable *atm_getvccs(struct atmio_vcc **, u_int, u_int,
struct mtx *, int);
#endif

57
sys/net/if_atmsubr.c
View file

@ -52,6 +52,7 @@ __FBSDID("$FreeBSD$");
#include <sys/sockio.h>
#include <sys/errno.h>
#include <sys/sysctl.h>
#include <sys/malloc.h>
#include <net/if.h>
#include <net/netisr.h>
@ -404,6 +405,62 @@ atm_ifdetach(struct ifnet *ifp)
if_detach(ifp);
}
/*
* Support routine for the SIOCATMGVCCS ioctl().
*
* This routine assumes, that the private VCC structures used by the driver
* begin with a struct atmio_vcc.
*
* Return a table of VCCs in a freshly allocated memory area.
* Here we have a problem: we first count, how many vccs we need
* to return. The we allocate the memory and finally fill it in.
* Because we cannot lock while calling malloc, the number of active
* vccs may change while we're in malloc. So we allocate a couple of
* vccs more and if space anyway is not enough re-iterate.
*
* We could use an sx lock for the vcc tables.
*/
struct atmio_vcctable *
atm_getvccs(struct atmio_vcc **table, u_int size, u_int start,
struct mtx *lock, int waitok)
{
u_int cid, alloc;
size_t len;
struct atmio_vcctable *vccs;
struct atmio_vcc *v;
alloc = start + 10;
vccs = NULL;
for (;;) {
len = sizeof(*vccs) + alloc * sizeof(vccs->vccs[0]);
vccs = reallocf(vccs, len, M_TEMP,
waitok ? M_WAITOK : M_NOWAIT);
if (vccs == NULL)
return (NULL);
bzero(vccs, len);
vccs->count = 0;
v = vccs->vccs;
mtx_lock(lock);
for (cid = 0; cid < size; cid++)
if (table[cid] != NULL) {
if (++vccs->count == alloc)
/* too many - try again */
break;
*v++ = *table[cid];
}
mtx_unlock(lock);
if (cid == size)
break;
alloc *= 2;
}
return (vccs);
}
static moduledata_t atm_mod = {
"atm",
NULL,