litmus-rt.git - The LITMUS^RT kernel.

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author	Chuck Ebbert <cebbert@redhat.com>	2008-04-15 17:34:47 -0400
committer	Linus Torvalds <torvalds@linux-foundation.org>	2008-04-15 22:35:41 -0400
commit	f0a37e008750ead1751b7d5e89d220a260a46147 (patch)
tree	db808d329fc56dee2c518a3964f94e25af9941d3 /drivers/acpi/bus.c
parent	d1e7780638a9192f15caf590e0081bf915fdef71 (diff)

acpi: bus: check once more for an empty list after locking it

List could have become empty after the unlocked check that was made earlier, so check again inside the lock. Should fix https://bugzilla.redhat.com/show_bug.cgi?id=427765 Signed-off-by: Chuck Ebbert <cebbert@redhat.com> Cc: <stable@kernel.org> Cc: Len Brown <lenb@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Diffstat (limited to 'drivers/acpi/bus.c')

-rw-r--r--

drivers/acpi/bus.c

1 files changed, 4 insertions, 3 deletions

         }
         spin_lock_irqsave(&acpi_bus_event_lock, flags);
-        entry =
+        if (!list_empty(&acpi_bus_event_list)) {
-            list_entry(acpi_bus_event_list.next, struct acpi_bus_event, node);
+                entry = list_entry(acpi_bus_event_list.next,
-        if (entry)
+                                   struct acpi_bus_event, node);
                 list_del(&entry->node);
+        }
         spin_unlock_irqrestore(&acpi_bus_event_lock, flags);
         if (!entry)

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/* * Copyright (C) 2006 Red Hat, Inc. All rights reserved. * * This copyrighted material is made available to anyone wishing to use, * modify, copy, or redistribute it subject to the terms and conditions * of the GNU General Public License v.2. */ #include <linux/miscdevice.h> #include <linux/init.h> #include <linux/wait.h> #include <linux/module.h> #include <linux/file.h> #include <linux/fs.h> #include <linux/poll.h> #include <linux/signal.h> #include <linux/spinlock.h> #include <linux/dlm.h> #include <linux/dlm_device.h> #include "dlm_internal.h" #include "lockspace.h" #include "lock.h" #include "lvb_table.h" static const char *name_prefix="dlm"; static struct miscdevice ctl_device; static struct file_operations device_fops; #ifdef CONFIG_COMPAT struct dlm_lock_params32 { __u8 mode; __u8 namelen; __u16 flags; __u32 lkid; __u32 parent; __u32 castparam; __u32 castaddr; __u32 bastparam; __u32 bastaddr; __u32 lksb; char lvb[DLM_USER_LVB_LEN]; char name[0]; }; struct dlm_write_request32 { __u32 version[3]; __u8 cmd; __u8 is64bit; __u8 unused[2]; union { struct dlm_lock_params32 lock; struct dlm_lspace_params lspace; } i; }; struct dlm_lksb32 { __u32 sb_status; __u32 sb_lkid; __u8 sb_flags; __u32 sb_lvbptr; }; struct dlm_lock_result32 { __u32 length; __u32 user_astaddr; __u32 user_astparam; __u32 user_lksb; struct dlm_lksb32 lksb; __u8 bast_mode; __u8 unused[3]; /* Offsets may be zero if no data is present */ __u32 lvb_offset; }; static void compat_input(struct dlm_write_request *kb, struct dlm_write_request32 *kb32) { kb->version[0] = kb32->version[0]; kb->version[1] = kb32->version[1]; kb->version[2] = kb32->version[2]; kb->cmd = kb32->cmd; kb->is64bit = kb32->is64bit; if (kb->cmd == DLM_USER_CREATE_LOCKSPACE || kb->cmd == DLM_USER_REMOVE_LOCKSPACE) { kb->i.lspace.flags = kb32->i.lspace.flags; kb->i.lspace.minor = kb32->i.lspace.minor; strcpy(kb->i.lspace.name, kb32->i.lspace.name); } else { kb->i.lock.mode = kb32->i.lock.mode; kb->i.lock.namelen = kb32->i.lock.namelen; kb->i.lock.flags = kb32->i.lock.flags; kb->i.lock.lkid = kb32->i.lock.lkid; kb->i.lock.parent = kb32->i.lock.parent; kb->i.lock.castparam = (void *)(long)kb32->i.lock.castparam; kb->i.lock.castaddr = (void *)(long)kb32->i.lock.castaddr; kb->i.lock.bastparam = (void *)(long)kb32->i.lock.bastparam; kb->i.lock.bastaddr = (void *)(long)kb32->i.lock.bastaddr; kb->i.lock.lksb = (void *)(long)kb32->i.lock.lksb; memcpy(kb->i.lock.lvb, kb32->i.lock.lvb, DLM_USER_LVB_LEN); memcpy(kb->i.lock.name, kb32->i.lock.name, kb->i.lock.namelen); } } static void compat_output(struct dlm_lock_result *res, struct dlm_lock_result32 *res32) { res32->length = res->length - (sizeof(struct dlm_lock_result) - sizeof(struct dlm_lock_result32)); res32->user_astaddr = (__u32)(long)res->user_astaddr; res32->user_astparam = (__u32)(long)res->user_astparam; res32->user_lksb = (__u32)(long)res->user_lksb; res32->bast_mode = res->bast_mode; res32->lvb_offset = res->lvb_offset; res32->length = res->length; res32->lksb.sb_status = res->lksb.sb_status; res32->lksb.sb_flags = res->lksb.sb_flags; res32->lksb.sb_lkid = res->lksb.sb_lkid; res32->lksb.sb_lvbptr = (__u32)(long)res->lksb.sb_lvbptr; } #endif void dlm_user_add_ast(struct dlm_lkb *lkb, int type) { struct dlm_ls *ls; struct dlm_user_args *ua; struct dlm_user_proc *proc; int remove_ownqueue = 0; /* dlm_clear_proc_locks() sets ORPHAN/DEAD flag on each lkb before dealing with it. We need to check this flag before taking ls_clear_proc_locks mutex because if it's set, dlm_clear_proc_locks() holds the mutex. */ if (lkb->lkb_flags & (DLM_IFL_ORPHAN | DLM_IFL_DEAD)) { /* log_print("user_add_ast skip1 %x", lkb->lkb_flags); */ return; } ls = lkb->lkb_resource->res_ls; mutex_lock(&ls->ls_clear_proc_locks); /* If ORPHAN/DEAD flag is set, it means the process is dead so an ast can't be delivered. For ORPHAN's, dlm_clear_proc_locks() freed lkb->ua so we can't try to use it. */ if (lkb->lkb_flags & (DLM_IFL_ORPHAN | DLM_IFL_DEAD)) { /* log_print("user_add_ast skip2 %x", lkb->lkb_flags); */ goto out; } DLM_ASSERT(lkb->lkb_astparam, dlm_print_lkb(lkb);); ua = (struct dlm_user_args *)lkb->lkb_astparam; proc = ua->proc; if (type == AST_BAST && ua->bastaddr == NULL) goto out; spin_lock(&proc->asts_spin); if (!(lkb->lkb_ast_type & (AST_COMP | AST_BAST))) { kref_get(&lkb->lkb_ref); list_add_tail(&lkb->lkb_astqueue, &proc->asts); lkb->lkb_ast_type |= type; wake_up_interruptible(&proc->wait); } /* noqueue requests that fail may need to be removed from the proc's locks list, there should be a better way of detecting this situation than checking all these things... */ if (type == AST_COMP && lkb->lkb_grmode == DLM_LOCK_IV && ua->lksb.sb_status == -EAGAIN && !list_empty(&lkb->lkb_ownqueue)) remove_ownqueue = 1; /* unlocks or cancels of waiting requests need to be removed from the proc's unlocking list, again there must be a better way... */ if (ua->lksb.sb_status == -DLM_EUNLOCK || (ua->lksb.sb_status == -DLM_ECANCEL && lkb->lkb_grmode == DLM_LOCK_IV)) remove_ownqueue = 1; /* We want to copy the lvb to userspace when the completion ast is read if the status is 0, the lock has an lvb and lvb_ops says we should. We could probably have set_lvb_lock() set update_user_lvb instead and not need old_mode */ if ((lkb->lkb_ast_type & AST_COMP) && (lkb->lkb_lksb->sb_status == 0) && lkb->lkb_lksb->sb_lvbptr && dlm_lvb_operations[ua->old_mode + 1][lkb->lkb_grmode + 1]) ua->update_user_lvb = 1; else ua->update_user_lvb = 0; spin_unlock(&proc->asts_spin); if (remove_ownqueue) { spin_lock(&ua->proc->locks_spin); list_del_init(&lkb->lkb_ownqueue); spin_unlock(&ua->proc->locks_spin); dlm_put_lkb(lkb); } out: mutex_unlock(&ls->ls_clear_proc_locks); } static int device_user_lock(struct dlm_user_proc *proc, struct dlm_lock_params *params) { struct dlm_ls *ls; struct dlm_user_args *ua; int error = -ENOMEM; ls = dlm_find_lockspace_local(proc->lockspace); if (!ls) return -ENOENT; if (!params->castaddr || !params->lksb) { error = -EINVAL; goto out; } ua = kzalloc(sizeof(struct dlm_user_args), GFP_KERNEL); if (!ua) goto out; ua->proc = proc; ua->user_lksb = params->lksb; ua->castparam = params->castparam; ua->castaddr = params->castaddr; ua->bastparam = params->bastparam; ua->bastaddr = params->bastaddr; if (params->flags & DLM_LKF_CONVERT) error = dlm_user_convert(ls, ua, params->mode, params->flags, params->lkid, params->lvb); else { error = dlm_user_request(ls, ua, params->mode, params->flags, params->name, params->namelen, params->parent); if (!error) error = ua->lksb.sb_lkid; } out: dlm_put_lockspace(ls); return error; } static int device_user_unlock(struct dlm_user_proc *proc, struct dlm_lock_params *params) { struct dlm_ls *ls; struct dlm_user_args *ua; int error = -ENOMEM; ls = dlm_find_lockspace_local(proc->lockspace); if (!ls) return -ENOENT; ua = kzalloc(sizeof(struct dlm_user_args), GFP_KERNEL); if (!ua) goto out; ua->proc = proc; ua->user_lksb = params->lksb; ua->castparam = params->castparam; ua->castaddr = params->castaddr; if (params->flags & DLM_LKF_CANCEL) error = dlm_user_cancel(ls, ua, params->flags, params->lkid); else error = dlm_user_unlock(ls, ua, params->flags, params->lkid, params->lvb); out: dlm_put_lockspace(ls); return error; } static int device_create_lockspace(struct dlm_lspace_params *params) { dlm_lockspace_t *lockspace; struct dlm_ls *ls; int error, len; if (!capable(CAP_SYS_ADMIN)) return -EPERM; error = dlm_new_lockspace(params->name, strlen(params->name), &lockspace, 0, DLM_USER_LVB_LEN); if (error) return error; ls = dlm_find_lockspace_local(lockspace); if (!ls) return -ENOENT; error = -ENOMEM; len = strlen(params->name) + strlen(name_prefix) + 2; ls->ls_device.name = kzalloc(len, GFP_KERNEL); if (!ls->ls_device.name) goto fail; snprintf((char *)ls->ls_device.name, len, "%s_%s", name_prefix, params->name); ls->ls_device.fops = &device_fops; ls->ls_device.minor = MISC_DYNAMIC_MINOR; error = misc_register(&ls->ls_device); if (error) { kfree(ls->ls_device.name); goto fail; } error = ls->ls_device.minor; dlm_put_lockspace(ls); return error; fail: dlm_put_lockspace(ls); dlm_release_lockspace(lockspace, 0); return error; } static int device_remove_lockspace(struct dlm_lspace_params *params) { dlm_lockspace_t *lockspace; struct dlm_ls *ls; int error, force = 0; if (!capable(CAP_SYS_ADMIN)) return -EPERM; ls = dlm_find_lockspace_device(params->minor); if (!ls) return -ENOENT;


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