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ifnet(9): split ifc_alloc_unit() (should simplify code flow)

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Allocate smallest unit number from pool via ifc_alloc_unit_next()
and exact unit number (if available) via ifc_alloc_unit_specific().

While here, address possible deadlock (mentioned in PR).

PR:		217401
MFC after:	5 days
Differential Revision:	https://reviews.freebsd.org/D12551
This commit is contained in:
Andriy Voskoboinyk 2017-10-16 21:21:31 +00:00
parent e9445808a8
commit c64c1f95a7
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=324672
1 changed files with 36 additions and 24 deletions
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60
sys/net/if_clone.c
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@ -595,39 +595,21 @@ ifc_name2unit(const char *name, int *unit)
return (0);
}
int
ifc_alloc_unit(struct if_clone *ifc, int *unit)
static int
ifc_alloc_unit_specific(struct if_clone *ifc, int *unit)
{
char name[IFNAMSIZ];
int wildcard;
wildcard = (*unit < 0);
retry:
if (*unit > ifc->ifc_maxunit)
return (ENOSPC);
if (*unit < 0) {
*unit = alloc_unr(ifc->ifc_unrhdr);
if (*unit == -1)
return (ENOSPC);
} else {
*unit = alloc_unr_specific(ifc->ifc_unrhdr, *unit);
if (*unit == -1) {
if (wildcard) {
(*unit)++;
goto retry;
} else
return (EEXIST);
}
}
if (alloc_unr_specific(ifc->ifc_unrhdr, *unit) == -1)
return (EEXIST);
snprintf(name, IFNAMSIZ, "%s%d", ifc->ifc_name, *unit);
if (ifunit(name) != NULL) {
free_unr(ifc->ifc_unrhdr, *unit);
if (wildcard) {
(*unit)++;
goto retry;
} else
return (EEXIST);
return (EEXIST);
}
IF_CLONE_ADDREF(ifc);
@ -635,6 +617,36 @@ ifc_alloc_unit(struct if_clone *ifc, int *unit)
return (0);
}
static int
ifc_alloc_unit_next(struct if_clone *ifc, int *unit)
{
int error;
*unit = alloc_unr(ifc->ifc_unrhdr);
if (*unit == -1)
return (ENOSPC);
free_unr(ifc->ifc_unrhdr, *unit);
for (;;) {
error = ifc_alloc_unit_specific(ifc, unit);
if (error != EEXIST)
break;
(*unit)++;
}
return (error);
}
int
ifc_alloc_unit(struct if_clone *ifc, int *unit)
{
if (*unit < 0)
return (ifc_alloc_unit_next(ifc, unit));
else
return (ifc_alloc_unit_specific(ifc, unit));
}
void
ifc_free_unit(struct if_clone *ifc, int unit)
{