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migration/rdma: Fix error handling around rdma_getaddrinfo() 

qemu_rdma_resolve_host() and qemu_rdma_dest_init() iterate over
addresses to find one that works, holding onto the first Error from
qemu_rdma_broken_ipv6_kernel() for use when no address works.  Issues:

1. If @errp was &error_abort or &error_fatal, we'd terminate instead
   of trying the next address.  Can't actually happen, since no caller
   passes these arguments.

2. When @errp is a pointer to a variable containing NULL, and
   qemu_rdma_broken_ipv6_kernel() fails, the variable no longer
   contains NULL.  Subsequent iterations pass it again, violating
   Error usage rules.  Dangerous, as setting an error would then trip
   error_setv()'s assertion.  Works only because
   qemu_rdma_broken_ipv6_kernel() and the code following the loops
   carefully avoids setting a second error.

3. If qemu_rdma_broken_ipv6_kernel() fails, and then a later iteration
   finds a working address, @errp still holds the first error from
   qemu_rdma_broken_ipv6_kernel().  If we then run into another error,
   we report the qemu_rdma_broken_ipv6_kernel() failure instead.

4. If we don't run into another error, we leak the Error object.

Use a local error variable, and propagate to @errp.  This fixes 3. and
also cleans up 1 and partly 2.

Free this error when we have a working address.  This fixes 4.

Pass the local error variable to qemu_rdma_broken_ipv6_kernel() only
until it fails.  Pass null on any later iterations.  This cleans up
the remainder of 2.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Li Zhijian <lizhijian@fujitsu.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
Message-ID: <20230928132019.2544702-34-armbru@redhat.com>
This commit is contained in:
Markus Armbruster 2023-09-28 15:19:59 +02:00 committed by Juan Quintela
parent 8fd471bd77
commit 071d5ae4f3
1 changed files with 21 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

25
migration/rdma.c
View File

@ -932,6 +932,7 @@ static int qemu_rdma_broken_ipv6_kernel(struct ibv_context *verbs, Error **errp)
*/
static int qemu_rdma_resolve_host(RDMAContext *rdma, Error **errp)
{
Error *err = NULL;
int ret;
struct rdma_addrinfo *res;
char port_str[16];
@ -976,7 +977,10 @@ static int qemu_rdma_resolve_host(RDMAContext *rdma, Error **errp)
goto err_resolve_get_addr;
}
/* Try all addresses, saving the first error in @err */
for (e = res; e != NULL; e = e->ai_next) {
Error **local_errp = err ? NULL : &err;
inet_ntop(e->ai_family,
&((struct sockaddr_in *) e->ai_dst_addr)->sin_addr, ip, sizeof ip);
trace_qemu_rdma_resolve_host_trying(rdma->host, ip);
@ -985,17 +989,21 @@ static int qemu_rdma_resolve_host(RDMAContext *rdma, Error **errp)
RDMA_RESOLVE_TIMEOUT_MS);
if (ret >= 0) {
if (e->ai_family == AF_INET6) {
ret = qemu_rdma_broken_ipv6_kernel(rdma->cm_id->verbs, errp);
ret = qemu_rdma_broken_ipv6_kernel(rdma->cm_id->verbs,
local_errp);
if (ret < 0) {
continue;
}
}
error_free(err);
goto route;
}
}
rdma_freeaddrinfo(res);
if (errp && !*errp) {
if (err) {
error_propagate(errp, err);
} else {
error_setg(errp, "RDMA ERROR: could not resolve address %s",
rdma->host);
}
@ -2707,6 +2715,7 @@ err_rdma_source_connect:
static int qemu_rdma_dest_init(RDMAContext *rdma, Error **errp)
{
Error *err = NULL;
int ret, idx;
struct rdma_cm_id *listen_id;
char ip[40] = "unknown";
@ -2765,7 +2774,11 @@ static int qemu_rdma_dest_init(RDMAContext *rdma, Error **errp)
}
goto err_dest_init_bind_addr;
}
/* Try all addresses, saving the first error in @err */
for (e = res; e != NULL; e = e->ai_next) {
Error **local_errp = err ? NULL : &err;
inet_ntop(e->ai_family,
&((struct sockaddr_in *) e->ai_dst_addr)->sin_addr, ip, sizeof ip);
trace_qemu_rdma_dest_init_trying(rdma->host, ip);
@ -2774,17 +2787,21 @@ static int qemu_rdma_dest_init(RDMAContext *rdma, Error **errp)
continue;
}
if (e->ai_family == AF_INET6) {
ret = qemu_rdma_broken_ipv6_kernel(listen_id->verbs, errp);
ret = qemu_rdma_broken_ipv6_kernel(listen_id->verbs,
local_errp);
if (ret < 0) {
continue;
}
}
error_free(err);
break;
}
rdma_freeaddrinfo(res);
if (!e) {
if (errp && !*errp) {
if (err) {
error_propagate(errp, err);
} else {
error_setg(errp, "RDMA ERROR: Error: could not rdma_bind_addr!");
}
goto err_dest_init_bind_addr;