[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH] linux-2.6.18/gnttab: add deferred freeing logic
Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx> --- a/drivers/xen/core/gnttab.c +++ b/drivers/xen/core/gnttab.c @@ -35,6 +35,7 @@ #include <linux/sched.h> #include <linux/mm.h> #include <linux/seqlock.h> +#include <linux/timer.h> #include <xen/interface/xen.h> #include <xen/gnttab.h> #include <asm/pgtable.h> @@ -183,35 +184,119 @@ int gnttab_query_foreign_access(grant_re } EXPORT_SYMBOL_GPL(gnttab_query_foreign_access); -int gnttab_end_foreign_access_ref(grant_ref_t ref) +static inline int _gnttab_end_foreign_access_ref(grant_ref_t ref) { u16 flags, nflags; nflags = shared[ref].flags; do { - if ((flags = nflags) & (GTF_reading|GTF_writing)) { - printk(KERN_DEBUG "WARNING: g.e. still in use!\n"); + if ((flags = nflags) & (GTF_reading|GTF_writing)) return 0; - } } while ((nflags = synch_cmpxchg_subword(&shared[ref].flags, flags, 0)) != flags); return 1; } + +int gnttab_end_foreign_access_ref(grant_ref_t ref) +{ + if (_gnttab_end_foreign_access_ref(ref)) + return 1; + printk(KERN_DEBUG "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; + 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)) { + put_free_entry(entry->ref); + if (entry->page) { + printk(KERN_DEBUG + "freeing g.e. %#x (pfn %#lx)\n", + entry->ref, page_to_pfn(entry->page)); + __free_page(entry->page); + } else + printk(KERN_DEBUG "freeing g.e. %#x\n", + entry->ref); + kfree(entry); + entry = NULL; + } else { + if (!--entry->warn_delay) + printk(KERN_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, 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->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, unsigned long page) { if (gnttab_end_foreign_access_ref(ref)) { 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_DEBUG - "WARNING: leaking g.e. and page still in use!\n"); - } + } else + gnttab_add_deferred(ref, page ? virt_to_page(page) : NULL); } EXPORT_SYMBOL_GPL(gnttab_end_foreign_access); Attachment:
xen-gnttab-deferred-end-access.patch _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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