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Do image loading in a context known to have a root directory:

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o create a private task queue thread that sets up root and current
  directories (hooking mountroot event as needed); this is necessary
  because task queue threads are parented from proc0 and it does not
  have a reference to rootvnode (lost when / mounting moved to init)
o bounce image load + unload requests through the private task q so
  we can load images even when the request is made from a thread that
  does not have sufficient context (e.g. task q thread)
o add a check in the task q thread to fail requests before root is
  mounted (just in case)

Reviewed by:	jhb, mlaier, luigi (glance)
MFC after:	1 month
This commit is contained in:
Sam Leffler 2008-04-09 19:07:48 +00:00
parent 8f9ac44aa7
commit 6c6eaea6dd
1 changed files with 122 additions and 24 deletions
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146
sys/kern/subr_firmware.c
View File

@ -1,5 +1,5 @@
/*-
* Copyright (c) 2005, Sam Leffler <sam@errno.com>
* Copyright (c) 2005-2008, Sam Leffler <sam@errno.com>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
@ -41,6 +41,10 @@ __FBSDID("$FreeBSD$");
#include <sys/priv.h>
#include <sys/proc.h>
#include <sys/module.h>
#include <sys/eventhandler.h>
#include <sys/filedesc.h>
#include <sys/vnode.h>
/*
* Loadable firmware support. See sys/sys/firmware.h and firmware(9)
@ -89,7 +93,7 @@ struct priv_fw {
/*
* 'file' is private info managed by the autoload/unload code.
* Set at the end of firmware_get(), cleared only in the
* firmware_task, so the latter can depend on its value even
* firmware_unload_task, so the latter can depend on its value even
* while the lock is not held.
*/
linker_file_t file; /* module file, if autoloaded */
@ -121,14 +125,16 @@ struct priv_fw {
static struct priv_fw firmware_table[FIRMWARE_MAX];
/*
* module release are handled in a separate task as they might sleep.
* Firmware module operations are handled in a separate task as they
* might sleep and they require directory context to do i/o.
*/
struct task firmware_task;
static struct taskqueue *firmware_tq;
static struct task firmware_unload_task;
/*
* This mutex protects accesses to the firmware table.
*/
struct mtx firmware_mtx;
static struct mtx firmware_mtx;
MTX_SYSINIT(firmware, &firmware_mtx, "firmware table", MTX_DEF);
/*
@ -227,7 +233,7 @@ firmware_unregister(const char *imagename)
} else if (fp->refcnt != 0) { /* cannot unregister */
err = EBUSY;
} else {
linker_file_t x = fp->file; /* save value */
linker_file_t x = fp->file; /* save value */
if (fp->parent != NULL) /* release parent reference */
fp->parent->refcnt--;
@ -244,6 +250,47 @@ firmware_unregister(const char *imagename)
return err;
}
static void
loadimage(void *arg, int npending)
{
struct thread *td = curthread;
char *imagename = arg;
struct priv_fw *fp;
linker_file_t result;
int error;
/* synchronize with the thread that dispatched us */
mtx_lock(&firmware_mtx);
mtx_unlock(&firmware_mtx);
if (td->td_proc->p_fd->fd_rdir == NULL) {
printf("%s: root not mounted yet, no way to load image\n",
imagename);
goto done;
}
error = linker_reference_module(imagename, NULL, &result);
if (error != 0) {
printf("%s: could not load firmware image, error %d\n",
imagename, error);
goto done;
}
mtx_lock(&firmware_mtx);
fp = lookup(imagename, NULL);
if (fp == NULL || fp->file != NULL) {
mtx_unlock(&firmware_mtx);
if (fp == NULL)
printf("%s: firmware image loaded, "
"but did not register\n", imagename);
(void) linker_release_module(imagename, NULL, NULL);
goto done;
}
fp->file = result; /* record the module identity */
mtx_unlock(&firmware_mtx);
done:
wakeup_one(imagename); /* we're done */
}
/*
* Lookup and potentially load the specified firmware image.
* If the firmware is not found in the registry, try to load a kernel
@ -254,9 +301,9 @@ firmware_unregister(const char *imagename)
const struct firmware *
firmware_get(const char *imagename)
{
struct task fwload_task;
struct thread *td;
struct priv_fw *fp;
linker_file_t result;
mtx_lock(&firmware_mtx);
fp = lookup(imagename, NULL);
@ -265,29 +312,30 @@ firmware_get(const char *imagename)
/*
* Image not present, try to load the module holding it.
*/
mtx_unlock(&firmware_mtx);
td = curthread;
if (priv_check(td, PRIV_FIRMWARE_LOAD) != 0 ||
securelevel_gt(td->td_ucred, 0) != 0) {
mtx_unlock(&firmware_mtx);
printf("%s: insufficient privileges to "
"load firmware image %s\n", __func__, imagename);
return NULL;
}
(void) linker_reference_module(imagename, NULL, &result);
/*
* After loading the module, see if the image is registered now.
/*
* Defer load to a thread with known context. linker_reference_module
* may do filesystem i/o which requires root & current dirs, etc.
* Also we must not hold any mtx's over this call which is problematic.
*/
TASK_INIT(&fwload_task, 0, loadimage, __DECONST(void *, imagename));
taskqueue_enqueue(firmware_tq, &fwload_task);
msleep(__DECONST(void *, imagename), &firmware_mtx, 0, "fwload", 0);
/*
* After attempting to load the module, see if the image is registered.
*/
mtx_lock(&firmware_mtx);
fp = lookup(imagename, NULL);
if (fp == NULL) {
mtx_unlock(&firmware_mtx);
printf("%s: failed to load firmware image %s\n",
__func__, imagename);
(void) linker_release_module(imagename, NULL, NULL);
return NULL;
}
fp->file = result; /* record the module identity */
found: /* common exit point on success */
fp->refcnt++;
mtx_unlock(&firmware_mtx);
@ -300,8 +348,8 @@ found: /* common exit point on success */
* to release the resource, but the flag is only advisory.
*
* If this is the last reference to the firmware image, and this is an
* autoloaded module, wake up the firmware_task to figure out what to do
* with the associated module.
* autoloaded module, wake up the firmware_unload_task to figure out
* what to do with the associated module.
*/
void
firmware_put(const struct firmware *p, int flags)
@ -314,11 +362,46 @@ firmware_put(const struct firmware *p, int flags)
if (flags & FIRMWARE_UNLOAD)
fp->flags |= FW_UNLOAD;
if (fp->file)
taskqueue_enqueue(taskqueue_thread, &firmware_task);
taskqueue_enqueue(firmware_tq, &firmware_unload_task);
}
mtx_unlock(&firmware_mtx);
}
/*
* Setup directory state for the firmware_tq thread so we can do i/o.
*/
static void
set_rootvnode(void *arg, int npending)
{
struct thread *td = curthread;
struct proc *p = td->td_proc;
FILEDESC_XLOCK(p->p_fd);
if (p->p_fd->fd_cdir == NULL) {
p->p_fd->fd_cdir = rootvnode;
VREF(rootvnode);
}
if (p->p_fd->fd_rdir == NULL) {
p->p_fd->fd_rdir = rootvnode;
VREF(rootvnode);
}
FILEDESC_XUNLOCK(p->p_fd);
}
/*
* Event handler called on mounting of /; bounce a task
* into the task queue thread to setup it's directories.
*/
static void
firmware_mountroot(void *arg)
{
static struct task setroot_task;
TASK_INIT(&setroot_task, 0, set_rootvnode, NULL);
taskqueue_enqueue(firmware_tq, &setroot_task);
}
EVENTHANDLER_DEFINE(mountroot, firmware_mountroot, NULL, 0);
/*
* The body of the task in charge of unloading autoloaded modules
* that are not needed anymore.
@ -383,11 +466,23 @@ static int
firmware_modevent(module_t mod, int type, void *unused)
{
struct priv_fw *fp;
int i, err = EINVAL;
int i, err;
switch (type) {
case MOD_LOAD:
TASK_INIT(&firmware_task, 0, unloadentry, NULL);
TASK_INIT(&firmware_unload_task, 0, unloadentry, NULL);
firmware_tq = taskqueue_create("taskqueue_firmware", M_WAITOK,
taskqueue_thread_enqueue, &firmware_tq);
/* NB: use our own loop routine that sets up context */
(void) taskqueue_start_threads(&firmware_tq, 1, PWAIT,
"firmware taskq");
if (rootvnode != NULL) {
/*
* Root is already mounted so we won't get an event;
* simulate one here.
*/
firmware_mountroot(NULL);
}
return 0;
case MOD_UNLOAD:
@ -398,8 +493,9 @@ firmware_modevent(module_t mod, int type, void *unused)
fp->flags |= FW_UNLOAD;;
}
mtx_unlock(&firmware_mtx);
taskqueue_enqueue(taskqueue_thread, &firmware_task);
taskqueue_drain(taskqueue_thread, &firmware_task);
taskqueue_enqueue(firmware_tq, &firmware_unload_task);
taskqueue_drain(firmware_tq, &firmware_unload_task);
err = 0;
for (i = 0; i < FIRMWARE_MAX; i++) {
fp = &firmware_table[i];
if (fp->fw.name != NULL) {
@ -409,6 +505,8 @@ firmware_modevent(module_t mod, int type, void *unused)
err = EINVAL;
}
}
if (err == 0)
taskqueue_free(firmware_tq);
return err;
}
return EINVAL;