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virNWFilterLockIface: Preserve correct lock ordering

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In the not so distant past, the lock ordering in
virNWFilterLockIface() was as follows: global mutex ifaceMapLock
was acquired, then internal representation of given interface was
looked up in a hash table (or created brand new if none was
found), the global lock was released and the lock of the
interface was acquired.

But this was mistakenly changed as the function was rewritten to
use automatic mutexes, because now the global lock is held
throughout the whole run of the function and thus the interface
specific lock is acquired with the global lock held. This results
in a deadlock.

Fixes: dd8150c48d
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
Tested-by: Erik Skultety <eskultet@redhat.com>
Reviewed-by: Erik Skultety <eskultet@redhat.com>
This commit is contained in:
Michal Privoznik 2022-03-18 17:14:54 +01:00
parent db7b0b12b7
commit af6f6091e0
1 changed files with 28 additions and 25 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

53
src/nwfilter/nwfilter_learnipaddr.c
View File

@ -143,37 +143,40 @@ static bool threadsTerminate;
int
virNWFilterLockIface(const char *ifname)
{
VIR_LOCK_GUARD lock = virLockGuardLock(&ifaceMapLock);
virNWFilterIfaceLock *ifaceLock = virHashLookup(ifaceLockMap, ifname);
virNWFilterIfaceLock *ifaceLock = NULL;
if (!ifaceLock) {
ifaceLock = g_new0(virNWFilterIfaceLock, 1);
VIR_WITH_MUTEX_LOCK_GUARD(&ifaceMapLock) {
ifaceLock = virHashLookup(ifaceLockMap, ifname);
if (virMutexInitRecursive(&ifaceLock->lock) < 0) {
virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
_("mutex initialization failed"));
g_free(ifaceLock);
return -1;
if (!ifaceLock) {
ifaceLock = g_new0(virNWFilterIfaceLock, 1);
if (virMutexInitRecursive(&ifaceLock->lock) < 0) {
virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
_("mutex initialization failed"));
g_free(ifaceLock);
return -1;
}
if (virStrcpyStatic(ifaceLock->ifname, ifname) < 0) {
virReportError(VIR_ERR_INTERNAL_ERROR,
_("interface name %s does not fit into buffer"),
ifaceLock->ifname);
g_free(ifaceLock);
return -1;
}
while (virHashAddEntry(ifaceLockMap, ifname, ifaceLock)) {
g_free(ifaceLock);
return -1;
}
ifaceLock->refctr = 0;
}
if (virStrcpyStatic(ifaceLock->ifname, ifname) < 0) {
virReportError(VIR_ERR_INTERNAL_ERROR,
_("interface name %s does not fit into buffer"),
ifaceLock->ifname);
g_free(ifaceLock);
return -1;
}
while (virHashAddEntry(ifaceLockMap, ifname, ifaceLock)) {
g_free(ifaceLock);
return -1;
}
ifaceLock->refctr = 0;
ifaceLock->refctr++;
}
ifaceLock->refctr++;
virMutexLock(&ifaceLock->lock);
return 0;