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When making a peer of unknown type framework tries to load module

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using linker_load_module(). This works OK if NGM_MKPEER message came
from userland and we have process associated with thread. But when
NGM_MKPEER was queued because target node was busy, linker_load_module()
is called from netisr thread leading to panic.
To workaround that we do not load modules by framework, instead ng_socket
loads module (if this is required) before sending NGM_MKPEER.
However, the race condition between return from NgSendMsg() and actual
creation of node still exist and needs to be solved.

PR:		kern/62789
Approved by:	julian
This commit is contained in:
Gleb Smirnoff 2004-07-27 20:30:56 +00:00
parent bad960b11b
commit 7610f57454
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=132705
3 changed files with 40 additions and 19 deletions
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1
sys/netgraph/netgraph.h
View File

@ -1059,6 +1059,7 @@ int ng_address_hook(node_p here, item_p item, hook_p hook, ng_ID_t retaddr);
int ng_address_path(node_p here, item_p item, char *address, ng_ID_t raddr);
int ng_bypass(hook_p hook1, hook_p hook2);
hook_p ng_findhook(node_p node, const char *name);
struct ng_type *ng_findtype(const char *type);
int ng_make_node_common(struct ng_type *typep, node_p *nodep);
int ng_name_node(node_p node, const char *name);
int ng_newtype(struct ng_type *tp);

24
sys/netgraph/ng_base.c
View File

@ -53,7 +53,6 @@
#include <sys/malloc.h>
#include <sys/syslog.h>
#include <sys/sysctl.h>
#include <sys/linker.h>
#include <sys/queue.h>
#include <sys/mbuf.h>
#include <sys/ctype.h>
@ -205,7 +204,6 @@ void ng_destroy_hook(hook_p hook);
node_p ng_name2noderef(node_p node, const char *name);
int ng_path2noderef(node_p here, const char *path,
node_p *dest, hook_p *lasthook);
struct ng_type *ng_findtype(const char *type);
int ng_make_node(const char *type, node_p *nodepp);
int ng_path_parse(char *addr, char **node, char **path, char **hook);
void ng_rmnode(node_p node, hook_p dummy1, void *dummy2, int dummy3);
@ -547,23 +545,11 @@ ng_make_node(const char *typename, node_p *nodepp)
return (EINVAL);
}
/* Locate the node type */
if ((type = ng_findtype(typename)) == NULL) {
char filename[NG_TYPESIZ + 3];
linker_file_t lf;
int error;
/* Not found, try to load it as a loadable module */
snprintf(filename, sizeof(filename), "ng_%s", typename);
error = linker_load_module(NULL, filename, NULL, NULL, &lf);
if (error != 0)
return (error);
lf->userrefs++; /* pretend loaded by the syscall */
/* Try again, as now the type should have linked itself in */
if ((type = ng_findtype(typename)) == NULL)
return (ENXIO);
}
/* Locate the node type. If we fail we return. Do not try to load
* module.
*/
if ((type = ng_findtype(typename)) == NULL)
return (ENXIO);
/*
* If we have a constructor, then make the node and

34
sys/netgraph/ng_socket.c
View File

@ -52,6 +52,7 @@
#include <sys/errno.h>
#include <sys/kdb.h>
#include <sys/kernel.h>
#include <sys/linker.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
@ -281,6 +282,39 @@ printf("errx=%d\n",error);
} while (0);
#else
/*
* Hack alert!
* We look into the message and if it mkpeers a node of unknown type, we
* try to load it. We need to do this now, in syscall thread, because if
* message gets queued and applied later we will get panic.
*/
if (msg->header.cmd == NGM_MKPEER) {
struct ngm_mkpeer *const mkp = (struct ngm_mkpeer *) msg->data;
struct ng_type *type;
if ((type = ng_findtype(mkp->type)) == NULL) {
char filename[NG_TYPESIZ + 3];
linker_file_t lf;
int error;
/* Not found, try to load it as a loadable module */
snprintf(filename, sizeof(filename), "ng_%s", mkp->type);
error = linker_load_module(NULL, filename, NULL, NULL, &lf);
if (error != 0) {
FREE(msg, M_NETGRAPH_MSG);
goto release;
}
lf->userrefs++;
/* Try again, as now the type should have linked itself in */
if ((type = ng_findtype(mkp->type)) == NULL) {
FREE(msg, M_NETGRAPH_MSG);
error = ENXIO;
goto release;
}
}
}
/* The callee will free the msg when done. The path is our business. */
NG_SEND_MSG_PATH(error, pcbp->sockdata->node, msg, path, 0);
#endif