mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-12-14 12:36:52 +07:00
f84adf4921
Replace llist_for_each_entry_safe with a while loop. llist_for_each_entry_safe can trigger a bug in GCC 4.1, so it's best to remove it and use a while loop and do the deletion manually. Specifically this bug can be triggered by hot-unplugging a disk, either by doing xm block-detach or by save/restore cycle. BUG: unable to handle kernel paging request at fffffffffffffff0 IP: [<ffffffffa0047223>] blkif_free+0x63/0x130 [xen_blkfront] The crash call trace is: ... bad_area_nosemaphore+0x13/0x20 do_page_fault+0x25e/0x4b0 page_fault+0x25/0x30 ? blkif_free+0x63/0x130 [xen_blkfront] blkfront_resume+0x46/0xa0 [xen_blkfront] xenbus_dev_resume+0x6c/0x140 pm_op+0x192/0x1b0 device_resume+0x82/0x1e0 dpm_resume+0xc9/0x1a0 dpm_resume_end+0x15/0x30 do_suspend+0x117/0x1e0 When drilling down to the assembler code, on newer GCC it does .L29: cmpq $-16, %r12 #, persistent_gnt check je .L30 #, out of the loop .L25: ... code in the loop testq %r13, %r13 # n je .L29 #, back to the top of the loop cmpq $-16, %r12 #, persistent_gnt check movq 16(%r12), %r13 # <variable>.node.next, n jne .L25 #, back to the top of the loop .L30: While on GCC 4.1, it is: L78: ... code in the loop testq %r13, %r13 # n je .L78 #, back to the top of the loop movq 16(%rbx), %r13 # <variable>.node.next, n jmp .L78 #, back to the top of the loop Which basically means that the exit loop condition instead of being: &(pos)->member != NULL; is: ; which makes the loop unbound. Since xen-blkfront is the only user of the llist_for_each_entry_safe macro remove it from llist.h. Orabug: 16263164 CC: stable@vger.kernel.org Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
187 lines
6.2 KiB
C
187 lines
6.2 KiB
C
#ifndef LLIST_H
|
|
#define LLIST_H
|
|
/*
|
|
* Lock-less NULL terminated single linked list
|
|
*
|
|
* If there are multiple producers and multiple consumers, llist_add
|
|
* can be used in producers and llist_del_all can be used in
|
|
* consumers. They can work simultaneously without lock. But
|
|
* llist_del_first can not be used here. Because llist_del_first
|
|
* depends on list->first->next does not changed if list->first is not
|
|
* changed during its operation, but llist_del_first, llist_add,
|
|
* llist_add (or llist_del_all, llist_add, llist_add) sequence in
|
|
* another consumer may violate that.
|
|
*
|
|
* If there are multiple producers and one consumer, llist_add can be
|
|
* used in producers and llist_del_all or llist_del_first can be used
|
|
* in the consumer.
|
|
*
|
|
* This can be summarized as follow:
|
|
*
|
|
* | add | del_first | del_all
|
|
* add | - | - | -
|
|
* del_first | | L | L
|
|
* del_all | | | -
|
|
*
|
|
* Where "-" stands for no lock is needed, while "L" stands for lock
|
|
* is needed.
|
|
*
|
|
* The list entries deleted via llist_del_all can be traversed with
|
|
* traversing function such as llist_for_each etc. But the list
|
|
* entries can not be traversed safely before deleted from the list.
|
|
* The order of deleted entries is from the newest to the oldest added
|
|
* one. If you want to traverse from the oldest to the newest, you
|
|
* must reverse the order by yourself before traversing.
|
|
*
|
|
* The basic atomic operation of this list is cmpxchg on long. On
|
|
* architectures that don't have NMI-safe cmpxchg implementation, the
|
|
* list can NOT be used in NMI handlers. So code that uses the list in
|
|
* an NMI handler should depend on CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG.
|
|
*
|
|
* Copyright 2010,2011 Intel Corp.
|
|
* Author: Huang Ying <ying.huang@intel.com>
|
|
*
|
|
* This program is free software; you can redistribute it and/or
|
|
* modify it under the terms of the GNU General Public License version
|
|
* 2 as published by the Free Software Foundation;
|
|
*
|
|
* This program is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
* GNU General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License
|
|
* along with this program; if not, write to the Free Software
|
|
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
|
|
*/
|
|
|
|
#include <linux/kernel.h>
|
|
#include <asm/cmpxchg.h>
|
|
|
|
struct llist_head {
|
|
struct llist_node *first;
|
|
};
|
|
|
|
struct llist_node {
|
|
struct llist_node *next;
|
|
};
|
|
|
|
#define LLIST_HEAD_INIT(name) { NULL }
|
|
#define LLIST_HEAD(name) struct llist_head name = LLIST_HEAD_INIT(name)
|
|
|
|
/**
|
|
* init_llist_head - initialize lock-less list head
|
|
* @head: the head for your lock-less list
|
|
*/
|
|
static inline void init_llist_head(struct llist_head *list)
|
|
{
|
|
list->first = NULL;
|
|
}
|
|
|
|
/**
|
|
* llist_entry - get the struct of this entry
|
|
* @ptr: the &struct llist_node pointer.
|
|
* @type: the type of the struct this is embedded in.
|
|
* @member: the name of the llist_node within the struct.
|
|
*/
|
|
#define llist_entry(ptr, type, member) \
|
|
container_of(ptr, type, member)
|
|
|
|
/**
|
|
* llist_for_each - iterate over some deleted entries of a lock-less list
|
|
* @pos: the &struct llist_node to use as a loop cursor
|
|
* @node: the first entry of deleted list entries
|
|
*
|
|
* In general, some entries of the lock-less list can be traversed
|
|
* safely only after being deleted from list, so start with an entry
|
|
* instead of list head.
|
|
*
|
|
* If being used on entries deleted from lock-less list directly, the
|
|
* traverse order is from the newest to the oldest added entry. If
|
|
* you want to traverse from the oldest to the newest, you must
|
|
* reverse the order by yourself before traversing.
|
|
*/
|
|
#define llist_for_each(pos, node) \
|
|
for ((pos) = (node); pos; (pos) = (pos)->next)
|
|
|
|
/**
|
|
* llist_for_each_entry - iterate over some deleted entries of lock-less list of given type
|
|
* @pos: the type * to use as a loop cursor.
|
|
* @node: the fist entry of deleted list entries.
|
|
* @member: the name of the llist_node with the struct.
|
|
*
|
|
* In general, some entries of the lock-less list can be traversed
|
|
* safely only after being removed from list, so start with an entry
|
|
* instead of list head.
|
|
*
|
|
* If being used on entries deleted from lock-less list directly, the
|
|
* traverse order is from the newest to the oldest added entry. If
|
|
* you want to traverse from the oldest to the newest, you must
|
|
* reverse the order by yourself before traversing.
|
|
*/
|
|
#define llist_for_each_entry(pos, node, member) \
|
|
for ((pos) = llist_entry((node), typeof(*(pos)), member); \
|
|
&(pos)->member != NULL; \
|
|
(pos) = llist_entry((pos)->member.next, typeof(*(pos)), member))
|
|
|
|
/**
|
|
* llist_empty - tests whether a lock-less list is empty
|
|
* @head: the list to test
|
|
*
|
|
* Not guaranteed to be accurate or up to date. Just a quick way to
|
|
* test whether the list is empty without deleting something from the
|
|
* list.
|
|
*/
|
|
static inline bool llist_empty(const struct llist_head *head)
|
|
{
|
|
return ACCESS_ONCE(head->first) == NULL;
|
|
}
|
|
|
|
static inline struct llist_node *llist_next(struct llist_node *node)
|
|
{
|
|
return node->next;
|
|
}
|
|
|
|
/**
|
|
* llist_add - add a new entry
|
|
* @new: new entry to be added
|
|
* @head: the head for your lock-less list
|
|
*
|
|
* Returns true if the list was empty prior to adding this entry.
|
|
*/
|
|
static inline bool llist_add(struct llist_node *new, struct llist_head *head)
|
|
{
|
|
struct llist_node *entry, *old_entry;
|
|
|
|
entry = head->first;
|
|
for (;;) {
|
|
old_entry = entry;
|
|
new->next = entry;
|
|
entry = cmpxchg(&head->first, old_entry, new);
|
|
if (entry == old_entry)
|
|
break;
|
|
}
|
|
|
|
return old_entry == NULL;
|
|
}
|
|
|
|
/**
|
|
* llist_del_all - delete all entries from lock-less list
|
|
* @head: the head of lock-less list to delete all entries
|
|
*
|
|
* If list is empty, return NULL, otherwise, delete all entries and
|
|
* return the pointer to the first entry. The order of entries
|
|
* deleted is from the newest to the oldest added one.
|
|
*/
|
|
static inline struct llist_node *llist_del_all(struct llist_head *head)
|
|
{
|
|
return xchg(&head->first, NULL);
|
|
}
|
|
|
|
extern bool llist_add_batch(struct llist_node *new_first,
|
|
struct llist_node *new_last,
|
|
struct llist_head *head);
|
|
extern struct llist_node *llist_del_first(struct llist_head *head);
|
|
|
|
#endif /* LLIST_H */
|