linux/fs/afs/server.c
Tejun Heo 41f63c5359 workqueue: use mod_delayed_work() instead of cancel + queue
Convert delayed_work users doing cancel_delayed_work() followed by
queue_delayed_work() to mod_delayed_work().

Most conversions are straight-forward.  Ones worth mentioning are,

* drivers/edac/edac_mc.c: edac_mc_workq_setup() converted to always
  use mod_delayed_work() and cancel loop in
  edac_mc_reset_delay_period() is dropped.

* drivers/platform/x86/thinkpad_acpi.c: No need to remember whether
  watchdog is active or not.  @fan_watchdog_active and related code
  dropped.

* drivers/power/charger-manager.c: Seemingly a lot of
  delayed_work_pending() abuse going on here.
  [delayed_]work_pending() are unsynchronized and racy when used like
  this.  I converted one instance in fullbatt_handler().  Please
  conver the rest so that it invokes workqueue APIs for the intended
  target state rather than trying to game work item pending state
  transitions.  e.g. if timer should be modified - call
  mod_delayed_work(), canceled - call cancel_delayed_work[_sync]().

* drivers/thermal/thermal_sys.c: thermal_zone_device_set_polling()
  simplified.  Note that round_jiffies() calls in this function are
  meaningless.  round_jiffies() work on absolute jiffies not delta
  delay used by delayed_work.

v2: Tomi pointed out that __cancel_delayed_work() users can't be
    safely converted to mod_delayed_work().  They could be calling it
    from irq context and if that happens while delayed_work_timer_fn()
    is running, it could deadlock.  __cancel_delayed_work() users are
    dropped.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Acked-by: Anton Vorontsov <cbouatmailru@gmail.com>
Acked-by: David Howells <dhowells@redhat.com>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Doug Thompson <dougthompson@xmission.com>
Cc: David Airlie <airlied@linux.ie>
Cc: Roland Dreier <roland@kernel.org>
Cc: "John W. Linville" <linville@tuxdriver.com>
Cc: Zhang Rui <rui.zhang@intel.com>
Cc: Len Brown <len.brown@intel.com>
Cc: "J. Bruce Fields" <bfields@fieldses.org>
Cc: Johannes Berg <johannes@sipsolutions.net>
2012-08-13 16:27:37 -07:00

322 lines
7.7 KiB
C

/* AFS server record management
*
* Copyright (C) 2002, 2007 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <linux/sched.h>
#include <linux/slab.h>
#include "internal.h"
static unsigned afs_server_timeout = 10; /* server timeout in seconds */
static void afs_reap_server(struct work_struct *);
/* tree of all the servers, indexed by IP address */
static struct rb_root afs_servers = RB_ROOT;
static DEFINE_RWLOCK(afs_servers_lock);
/* LRU list of all the servers not currently in use */
static LIST_HEAD(afs_server_graveyard);
static DEFINE_SPINLOCK(afs_server_graveyard_lock);
static DECLARE_DELAYED_WORK(afs_server_reaper, afs_reap_server);
/*
* install a server record in the master tree
*/
static int afs_install_server(struct afs_server *server)
{
struct afs_server *xserver;
struct rb_node **pp, *p;
int ret;
_enter("%p", server);
write_lock(&afs_servers_lock);
ret = -EEXIST;
pp = &afs_servers.rb_node;
p = NULL;
while (*pp) {
p = *pp;
_debug("- consider %p", p);
xserver = rb_entry(p, struct afs_server, master_rb);
if (server->addr.s_addr < xserver->addr.s_addr)
pp = &(*pp)->rb_left;
else if (server->addr.s_addr > xserver->addr.s_addr)
pp = &(*pp)->rb_right;
else
goto error;
}
rb_link_node(&server->master_rb, p, pp);
rb_insert_color(&server->master_rb, &afs_servers);
ret = 0;
error:
write_unlock(&afs_servers_lock);
return ret;
}
/*
* allocate a new server record
*/
static struct afs_server *afs_alloc_server(struct afs_cell *cell,
const struct in_addr *addr)
{
struct afs_server *server;
_enter("");
server = kzalloc(sizeof(struct afs_server), GFP_KERNEL);
if (server) {
atomic_set(&server->usage, 1);
server->cell = cell;
INIT_LIST_HEAD(&server->link);
INIT_LIST_HEAD(&server->grave);
init_rwsem(&server->sem);
spin_lock_init(&server->fs_lock);
server->fs_vnodes = RB_ROOT;
server->cb_promises = RB_ROOT;
spin_lock_init(&server->cb_lock);
init_waitqueue_head(&server->cb_break_waitq);
INIT_DELAYED_WORK(&server->cb_break_work,
afs_dispatch_give_up_callbacks);
memcpy(&server->addr, addr, sizeof(struct in_addr));
server->addr.s_addr = addr->s_addr;
_leave(" = %p{%d}", server, atomic_read(&server->usage));
} else {
_leave(" = NULL [nomem]");
}
return server;
}
/*
* get an FS-server record for a cell
*/
struct afs_server *afs_lookup_server(struct afs_cell *cell,
const struct in_addr *addr)
{
struct afs_server *server, *candidate;
_enter("%p,%pI4", cell, &addr->s_addr);
/* quick scan of the list to see if we already have the server */
read_lock(&cell->servers_lock);
list_for_each_entry(server, &cell->servers, link) {
if (server->addr.s_addr == addr->s_addr)
goto found_server_quickly;
}
read_unlock(&cell->servers_lock);
candidate = afs_alloc_server(cell, addr);
if (!candidate) {
_leave(" = -ENOMEM");
return ERR_PTR(-ENOMEM);
}
write_lock(&cell->servers_lock);
/* check the cell's server list again */
list_for_each_entry(server, &cell->servers, link) {
if (server->addr.s_addr == addr->s_addr)
goto found_server;
}
_debug("new");
server = candidate;
if (afs_install_server(server) < 0)
goto server_in_two_cells;
afs_get_cell(cell);
list_add_tail(&server->link, &cell->servers);
write_unlock(&cell->servers_lock);
_leave(" = %p{%d}", server, atomic_read(&server->usage));
return server;
/* found a matching server quickly */
found_server_quickly:
_debug("found quickly");
afs_get_server(server);
read_unlock(&cell->servers_lock);
no_longer_unused:
if (!list_empty(&server->grave)) {
spin_lock(&afs_server_graveyard_lock);
list_del_init(&server->grave);
spin_unlock(&afs_server_graveyard_lock);
}
_leave(" = %p{%d}", server, atomic_read(&server->usage));
return server;
/* found a matching server on the second pass */
found_server:
_debug("found");
afs_get_server(server);
write_unlock(&cell->servers_lock);
kfree(candidate);
goto no_longer_unused;
/* found a server that seems to be in two cells */
server_in_two_cells:
write_unlock(&cell->servers_lock);
kfree(candidate);
printk(KERN_NOTICE "kAFS: Server %pI4 appears to be in two cells\n",
addr);
_leave(" = -EEXIST");
return ERR_PTR(-EEXIST);
}
/*
* look up a server by its IP address
*/
struct afs_server *afs_find_server(const struct in_addr *_addr)
{
struct afs_server *server = NULL;
struct rb_node *p;
struct in_addr addr = *_addr;
_enter("%pI4", &addr.s_addr);
read_lock(&afs_servers_lock);
p = afs_servers.rb_node;
while (p) {
server = rb_entry(p, struct afs_server, master_rb);
_debug("- consider %p", p);
if (addr.s_addr < server->addr.s_addr) {
p = p->rb_left;
} else if (addr.s_addr > server->addr.s_addr) {
p = p->rb_right;
} else {
afs_get_server(server);
goto found;
}
}
server = NULL;
found:
read_unlock(&afs_servers_lock);
ASSERTIFCMP(server, server->addr.s_addr, ==, addr.s_addr);
_leave(" = %p", server);
return server;
}
/*
* destroy a server record
* - removes from the cell list
*/
void afs_put_server(struct afs_server *server)
{
if (!server)
return;
_enter("%p{%d}", server, atomic_read(&server->usage));
_debug("PUT SERVER %d", atomic_read(&server->usage));
ASSERTCMP(atomic_read(&server->usage), >, 0);
if (likely(!atomic_dec_and_test(&server->usage))) {
_leave("");
return;
}
afs_flush_callback_breaks(server);
spin_lock(&afs_server_graveyard_lock);
if (atomic_read(&server->usage) == 0) {
list_move_tail(&server->grave, &afs_server_graveyard);
server->time_of_death = get_seconds();
queue_delayed_work(afs_wq, &afs_server_reaper,
afs_server_timeout * HZ);
}
spin_unlock(&afs_server_graveyard_lock);
_leave(" [dead]");
}
/*
* destroy a dead server
*/
static void afs_destroy_server(struct afs_server *server)
{
_enter("%p", server);
ASSERTIF(server->cb_break_head != server->cb_break_tail,
delayed_work_pending(&server->cb_break_work));
ASSERTCMP(server->fs_vnodes.rb_node, ==, NULL);
ASSERTCMP(server->cb_promises.rb_node, ==, NULL);
ASSERTCMP(server->cb_break_head, ==, server->cb_break_tail);
ASSERTCMP(atomic_read(&server->cb_break_n), ==, 0);
afs_put_cell(server->cell);
kfree(server);
}
/*
* reap dead server records
*/
static void afs_reap_server(struct work_struct *work)
{
LIST_HEAD(corpses);
struct afs_server *server;
unsigned long delay, expiry;
time_t now;
now = get_seconds();
spin_lock(&afs_server_graveyard_lock);
while (!list_empty(&afs_server_graveyard)) {
server = list_entry(afs_server_graveyard.next,
struct afs_server, grave);
/* the queue is ordered most dead first */
expiry = server->time_of_death + afs_server_timeout;
if (expiry > now) {
delay = (expiry - now) * HZ;
mod_delayed_work(afs_wq, &afs_server_reaper, delay);
break;
}
write_lock(&server->cell->servers_lock);
write_lock(&afs_servers_lock);
if (atomic_read(&server->usage) > 0) {
list_del_init(&server->grave);
} else {
list_move_tail(&server->grave, &corpses);
list_del_init(&server->link);
rb_erase(&server->master_rb, &afs_servers);
}
write_unlock(&afs_servers_lock);
write_unlock(&server->cell->servers_lock);
}
spin_unlock(&afs_server_graveyard_lock);
/* now reap the corpses we've extracted */
while (!list_empty(&corpses)) {
server = list_entry(corpses.next, struct afs_server, grave);
list_del(&server->grave);
afs_destroy_server(server);
}
}
/*
* discard all the server records for rmmod
*/
void __exit afs_purge_servers(void)
{
afs_server_timeout = 0;
mod_delayed_work(afs_wq, &afs_server_reaper, 0);
}