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Code Issues Releases Activity

Make system call modules a bit more robust:

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- If we fail to register the system call during MOD_LOAD, then note that
  so that we don't try to deregister it or invoke the chained event handler
  during the subsequent MOD_UNLOAD event.  Doing the deregister when the
  register failed could result in trashing system call entries.
- Add a SI_SUB_SYSCALLS just before starting up init and use that to
  register syscall modules instead of SI_SUB_DRIVERS.  Registering system
  calls as late as possible increases the chances that any other module
  event handlers or SYSINITs in a module are executed to initialize the
  data in a kld before a syscall dependent on that data is able to be
  invoked.

MFC after:	3 days
This commit is contained in:
John Baldwin 2006-08-01 16:32:20 +00:00
parent 6cba7f3609
commit 03e161fdb1
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=160882
3 changed files with 13 additions and 2 deletions
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12
sys/kern/kern_syscalls.c
View File

@ -97,8 +97,11 @@ syscall_module_handler(struct module *mod, int what, void *arg)
case MOD_LOAD :
error = syscall_register(data->offset, data->new_sysent,
&data->old_sysent);
if (error)
if (error) {
/* Leave a mark so we know to safely unload below. */
data->offset = NULL;
return error;
}
ms.intval = *data->offset;
MOD_XLOCK;
module_setspecific(mod, &ms);
@ -108,6 +111,13 @@ syscall_module_handler(struct module *mod, int what, void *arg)
return error;
case MOD_UNLOAD :
/*
* MOD_LOAD failed, so just return without calling the
* chained handler since we didn't pass along the MOD_LOAD
* event.
*/
if (data->offset == NULL)
return (0);
if (data->chainevh) {
error = data->chainevh(mod, what, data->chainarg);
if (error)

1
sys/sys/kernel.h
View File

@ -157,6 +157,7 @@ enum sysinit_sub_id {
SI_SUB_MOUNT_ROOT = 0xb400000, /* root mount*/
SI_SUB_SWAP = 0xc000000, /* swap */
SI_SUB_INTRINSIC_POST = 0xd000000, /* proc 0 cleanup*/
SI_SUB_SYSCALLS = 0xd800000, /* register system calls */
SI_SUB_KTHREAD_INIT = 0xe000000, /* init process*/
SI_SUB_KTHREAD_PAGE = 0xe400000, /* pageout daemon*/
SI_SUB_KTHREAD_VM = 0xe800000, /* vm daemon*/

2
sys/sys/sysent.h
View File

@ -113,7 +113,7 @@ static moduledata_t name##_mod = { \
syscall_module_handler, \
&name##_syscall_mod \
}; \
DECLARE_MODULE(name, name##_mod, SI_SUB_DRIVERS, SI_ORDER_MIDDLE)
DECLARE_MODULE(name, name##_mod, SI_SUB_SYSCALLS, SI_ORDER_MIDDLE)
#define SYSCALL_MODULE_HELPER(syscallname) \
static int syscallname##_syscall = SYS_##syscallname; \