diff options
author | Jan Beulich <JBeulich@suse.com> | 2012-04-05 17:10:07 +0200 |
---|---|---|
committer | Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> | 2012-04-17 19:29:13 +0200 |
commit | 569ca5b3f94cd0b3295ec5943aa457cf4a4f6a3a (patch) | |
tree | 5771fbace4a88ef1feb29f5dd4096f8ba4c9009b /drivers | |
parent | debugfs: Add support to print u32 array in debugfs (diff) | |
download | linux-569ca5b3f94cd0b3295ec5943aa457cf4a4f6a3a.tar.xz linux-569ca5b3f94cd0b3295ec5943aa457cf4a4f6a3a.zip |
xen/gnttab: add deferred freeing logic
Rather than just leaking pages that can't be freed at the point where
access permission for the backend domain gets revoked, put them on a
list and run a timer to (infrequently) retry freeing them. (This can
particularly happen when unloading a frontend driver when devices are
still present, and the backend still has them in non-closed state or
hasn't finished closing them yet.)
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Diffstat (limited to 'drivers')
-rw-r--r-- | drivers/xen/grant-table.c | 106 |
1 files changed, 96 insertions, 10 deletions
diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c index b4d4eac761db..9f514bb561af 100644 --- a/drivers/xen/grant-table.c +++ b/drivers/xen/grant-table.c @@ -426,10 +426,8 @@ static int gnttab_end_foreign_access_ref_v1(grant_ref_t ref, int readonly) nflags = *pflags; do { flags = nflags; - if (flags & (GTF_reading|GTF_writing)) { - printk(KERN_ALERT "WARNING: g.e. still in use!\n"); + if (flags & (GTF_reading|GTF_writing)) return 0; - } } while ((nflags = sync_cmpxchg(pflags, flags, 0)) != flags); return 1; @@ -458,12 +456,103 @@ static int gnttab_end_foreign_access_ref_v2(grant_ref_t ref, int readonly) return 1; } -int gnttab_end_foreign_access_ref(grant_ref_t ref, int readonly) +static inline int _gnttab_end_foreign_access_ref(grant_ref_t ref, int readonly) { return gnttab_interface->end_foreign_access_ref(ref, readonly); } + +int gnttab_end_foreign_access_ref(grant_ref_t ref, int readonly) +{ + if (_gnttab_end_foreign_access_ref(ref, readonly)) + return 1; + pr_warn("WARNING: g.e. %#x still in use!\n", ref); + return 0; +} EXPORT_SYMBOL_GPL(gnttab_end_foreign_access_ref); +struct deferred_entry { + struct list_head list; + grant_ref_t ref; + bool ro; + uint16_t warn_delay; + struct page *page; +}; +static LIST_HEAD(deferred_list); +static void gnttab_handle_deferred(unsigned long); +static DEFINE_TIMER(deferred_timer, gnttab_handle_deferred, 0, 0); + +static void gnttab_handle_deferred(unsigned long unused) +{ + unsigned int nr = 10; + struct deferred_entry *first = NULL; + unsigned long flags; + + spin_lock_irqsave(&gnttab_list_lock, flags); + while (nr--) { + struct deferred_entry *entry + = list_first_entry(&deferred_list, + struct deferred_entry, list); + + if (entry == first) + break; + list_del(&entry->list); + spin_unlock_irqrestore(&gnttab_list_lock, flags); + if (_gnttab_end_foreign_access_ref(entry->ref, entry->ro)) { + put_free_entry(entry->ref); + if (entry->page) { + pr_debug("freeing g.e. %#x (pfn %#lx)\n", + entry->ref, page_to_pfn(entry->page)); + __free_page(entry->page); + } else + pr_info("freeing g.e. %#x\n", entry->ref); + kfree(entry); + entry = NULL; + } else { + if (!--entry->warn_delay) + pr_info("g.e. %#x still pending\n", + entry->ref); + if (!first) + first = entry; + } + spin_lock_irqsave(&gnttab_list_lock, flags); + if (entry) + list_add_tail(&entry->list, &deferred_list); + else if (list_empty(&deferred_list)) + break; + } + if (!list_empty(&deferred_list) && !timer_pending(&deferred_timer)) { + deferred_timer.expires = jiffies + HZ; + add_timer(&deferred_timer); + } + spin_unlock_irqrestore(&gnttab_list_lock, flags); +} + +static void gnttab_add_deferred(grant_ref_t ref, bool readonly, + struct page *page) +{ + struct deferred_entry *entry = kmalloc(sizeof(*entry), GFP_ATOMIC); + const char *what = KERN_WARNING "leaking"; + + if (entry) { + unsigned long flags; + + entry->ref = ref; + entry->ro = readonly; + entry->page = page; + entry->warn_delay = 60; + spin_lock_irqsave(&gnttab_list_lock, flags); + list_add_tail(&entry->list, &deferred_list); + if (!timer_pending(&deferred_timer)) { + deferred_timer.expires = jiffies + HZ; + add_timer(&deferred_timer); + } + spin_unlock_irqrestore(&gnttab_list_lock, flags); + what = KERN_DEBUG "deferring"; + } + printk("%s g.e. %#x (pfn %#lx)\n", + what, ref, page ? page_to_pfn(page) : -1); +} + void gnttab_end_foreign_access(grant_ref_t ref, int readonly, unsigned long page) { @@ -471,12 +560,9 @@ void gnttab_end_foreign_access(grant_ref_t ref, int readonly, put_free_entry(ref); if (page != 0) free_page(page); - } else { - /* XXX This needs to be fixed so that the ref and page are - placed on a list to be freed up later. */ - printk(KERN_WARNING - "WARNING: leaking g.e. and page still in use!\n"); - } + } else + gnttab_add_deferred(ref, readonly, + page ? virt_to_page(page) : NULL); } EXPORT_SYMBOL_GPL(gnttab_end_foreign_access); |