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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v2 3/6] mm: Use statically defined locking order
On 08/03/17 17:46, Ross Lagerwall wrote:
> Instead of using a locking order based on line numbers which interacts
> poorly with trying to create a live patch, statically define the locking
> order.
>
> Signed-off-by: Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>
> Reviewed-by: Dario Faggioli <dario.faggioli@xxxxxxxxxx>
Acked-by: George Dunlap <george.dunlap@xxxxxxxxxx>
> ---
>
> Changes in v2:
> * Rearranged defines.
> * Make lock orders fit in a sign-extended 8-bit immediate.
>
> xen/arch/x86/mm/mm-locks.h | 28 +++++++++++++++++++---------
> 1 file changed, 19 insertions(+), 9 deletions(-)
>
> diff --git a/xen/arch/x86/mm/mm-locks.h b/xen/arch/x86/mm/mm-locks.h
> index 74fdfc1..e5fceb2 100644
> --- a/xen/arch/x86/mm/mm-locks.h
> +++ b/xen/arch/x86/mm/mm-locks.h
> @@ -46,8 +46,10 @@ static inline int mm_locked_by_me(mm_lock_t *l)
> return (l->lock.recurse_cpu == current->processor);
> }
>
> -/* If you see this crash, the numbers printed are lines in this file
> - * where the offending locks are declared. */
> +/*
> + * If you see this crash, the numbers printed are order levels defined
> + * in this file.
> + */
> #define __check_lock_level(l) \
> do { \
> if ( unlikely(__get_lock_level() > (l)) ) \
> @@ -152,12 +154,12 @@ static inline void mm_read_unlock(mm_rwlock_t *l)
> /* This wrapper uses the line number to express the locking order below */
> #define declare_mm_lock(name)
> \
> static inline void mm_lock_##name(mm_lock_t *l, const char *func, int
> rec)\
> - { _mm_lock(l, func, __LINE__, rec); }
> + { _mm_lock(l, func, MM_LOCK_ORDER_##name, rec); }
> #define declare_mm_rwlock(name)
> \
> static inline void mm_write_lock_##name(mm_rwlock_t *l, const char
> *func) \
> - { _mm_write_lock(l, func, __LINE__); }
> \
> + { _mm_write_lock(l, func, MM_LOCK_ORDER_##name); }
> \
> static inline void mm_read_lock_##name(mm_rwlock_t *l)
> \
> - { _mm_read_lock(l, __LINE__); }
> + { _mm_read_lock(l, MM_LOCK_ORDER_##name); }
> /* These capture the name of the calling function */
> #define mm_lock(name, l) mm_lock_##name(l, __func__, 0)
> #define mm_lock_recursive(name, l) mm_lock_##name(l, __func__, 1)
> @@ -169,10 +171,10 @@ static inline void mm_read_unlock(mm_rwlock_t *l)
> * to ordering constraints. */
> #define declare_mm_order_constraint(name) \
> static inline void mm_enforce_order_lock_pre_##name(void) \
> - { _mm_enforce_order_lock_pre(__LINE__); } \
> + { _mm_enforce_order_lock_pre(MM_LOCK_ORDER_##name); }
> \
> static inline void mm_enforce_order_lock_post_##name( \
> int *unlock_level, unsigned short *recurse_count) \
> - { _mm_enforce_order_lock_post(__LINE__, unlock_level, recurse_count); } \
> + { _mm_enforce_order_lock_post(MM_LOCK_ORDER_##name, unlock_level,
> recurse_count); } \
>
> static inline void mm_unlock(mm_lock_t *l)
> {
> @@ -201,8 +203,8 @@ static inline void mm_enforce_order_unlock(int
> unlock_level,
>
> /************************************************************************
> * *
> - * To avoid deadlocks, these locks _MUST_ be taken in the order they're *
> - * declared in this file. The locking functions will enforce this. *
> + * To avoid deadlocks, these locks _MUST_ be taken in the order listed *
> + * below. The locking functions will enforce this. *
> * *
> ************************************************************************/
>
> @@ -214,6 +216,7 @@ static inline void mm_enforce_order_unlock(int
> unlock_level,
> * - setting the "cr3" field of any p2m table to a non-P2M_BASE_EAADR value.
> * (i.e. assigning a p2m table to be the shadow of that cr3 */
>
> +#define MM_LOCK_ORDER_nestedp2m 8
> declare_mm_lock(nestedp2m)
> #define nestedp2m_lock(d) mm_lock(nestedp2m, &(d)->arch.nested_p2m_lock)
> #define nestedp2m_unlock(d) mm_unlock(&(d)->arch.nested_p2m_lock)
> @@ -240,6 +243,7 @@ declare_mm_lock(nestedp2m)
> * the altp2mlist lock in the middle.
> */
>
> +#define MM_LOCK_ORDER_p2m 16
> declare_mm_rwlock(p2m);
>
> /* Sharing per page lock
> @@ -251,6 +255,7 @@ declare_mm_rwlock(p2m);
> *
> * The lock is recursive because during share we lock two pages. */
>
> +#define MM_LOCK_ORDER_per_page_sharing 24
> declare_mm_order_constraint(per_page_sharing)
> #define page_sharing_mm_pre_lock()
> mm_enforce_order_lock_pre_per_page_sharing()
> #define page_sharing_mm_post_lock(l, r) \
> @@ -265,6 +270,7 @@ declare_mm_order_constraint(per_page_sharing)
> * in the target domain must be paused.
> */
>
> +#define MM_LOCK_ORDER_altp2mlist 32
> declare_mm_lock(altp2mlist)
> #define altp2m_list_lock(d) mm_lock(altp2mlist,
> &(d)->arch.altp2m_list_lock)
> #define altp2m_list_unlock(d) mm_unlock(&(d)->arch.altp2m_list_lock)
> @@ -279,6 +285,7 @@ declare_mm_lock(altp2mlist)
> * up a gfn and later mutate it.
> */
>
> +#define MM_LOCK_ORDER_altp2m 40
> declare_mm_rwlock(altp2m);
> #define p2m_lock(p) \
> do { \
> @@ -307,6 +314,7 @@ declare_mm_rwlock(altp2m);
> * Protects private PoD data structs: entry and cache
> * counts, page lists, sweep parameters. */
>
> +#define MM_LOCK_ORDER_pod 48
> declare_mm_lock(pod)
> #define pod_lock(p) mm_lock(pod, &(p)->pod.lock)
> #define pod_unlock(p) mm_unlock(&(p)->pod.lock)
> @@ -319,6 +327,7 @@ declare_mm_lock(pod)
> * the ordering which we enforce here.
> * The lock is not recursive. */
>
> +#define MM_LOCK_ORDER_page_alloc 56
> declare_mm_order_constraint(page_alloc)
> #define page_alloc_mm_pre_lock() mm_enforce_order_lock_pre_page_alloc()
> #define page_alloc_mm_post_lock(l)
> mm_enforce_order_lock_post_page_alloc(&(l), NULL)
> @@ -339,6 +348,7 @@ declare_mm_order_constraint(page_alloc)
> * It also protects the log-dirty bitmap from concurrent accesses (and
> * teardowns, etc). */
>
> +#define MM_LOCK_ORDER_paging 64
> declare_mm_lock(paging)
> #define paging_lock(d) mm_lock(paging, &(d)->arch.paging.lock)
> #define paging_lock_recursive(d) \
>
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