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IB: Improve uverbs_cleanup_ucontext algorithm

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Improve uverbs_cleanup_ucontext algorithm to work properly when the
topology graph of the objects cannot be determined at compile time.  This
is the case with objects created via the devx interface in mlx5.

Typically uverbs objects must be created in a strict topologically sorted
order, so that LIFO ordering will generally cause them to be freed
properly. There are only a few cases (eg memory windows) where objects can
point to things out of the strict LIFO order.

Instead of using an explicit ordering scheme where the HW destroy is not
allowed to fail, go over the list multiple times and allow the destroy
function to fail. If progress halts then a final, desperate, cleanup is
done before leaking the memory. This indicates a driver bug.

Signed-off-by: Yishai Hadas <[email protected]>
Signed-off-by: Leon Romanovsky <[email protected]>
Signed-off-by: Jason Gunthorpe <[email protected]>
This commit is contained in:
Yishai Hadas 2018-06-20 17:11:39 +03:00 • committed by Jason Gunthorpe
commit 1c77483e4c
12 changed files with 190 additions and 111 deletions
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46
include/rdma/ib_verbs.h
View file

@ -1476,7 +1476,10 @@ struct ib_fmr_attr {
struct ib_umem;
enum rdma_remove_reason {
/* Userspace requested uobject deletion. Call could fail */
/*
* Userspace requested uobject deletion or initial try
* to remove uobject via cleanup. Call could fail
*/
RDMA_REMOVE_DESTROY,
/* Context deletion. This call should delete the actual object itself */
RDMA_REMOVE_CLOSE,
@ -1503,6 +1506,7 @@ struct ib_ucontext {
/* protects cleanup process from other actions */
struct rw_semaphore cleanup_rwsem;
enum rdma_remove_reason cleanup_reason;
bool cleanup_retryable;
struct pid *tgid;
#ifdef CONFIG_INFINIBAND_ON_DEMAND_PAGING
@ -2684,6 +2688,46 @@ static inline bool ib_is_udata_cleared(struct ib_udata *udata,
return ib_is_buffer_cleared(udata->inbuf + offset, len);
}
/**
* ib_is_destroy_retryable - Check whether the uobject destruction
* is retryable.
* @ret: The initial destruction return code
* @why: remove reason
* @uobj: The uobject that is destroyed
*
* This function is a helper function that IB layer and low-level drivers
* can use to consider whether the destruction of the given uobject is
* retry-able.
* It checks the original return code, if it wasn't success the destruction
* is retryable according to the ucontext state (i.e. cleanup_retryable) and
* the remove reason. (i.e. why).
* Must be called with the object locked for destroy.
*/
static inline bool ib_is_destroy_retryable(int ret, enum rdma_remove_reason why,
struct ib_uobject *uobj)
{
return ret && (why == RDMA_REMOVE_DESTROY ||
uobj->context->cleanup_retryable);
}
/**
* ib_destroy_usecnt - Called during destruction to check the usecnt
* @usecnt: The usecnt atomic
* @why: remove reason
* @uobj: The uobject that is destroyed
*
* Non-zero usecnts will block destruction unless destruction was triggered by
* a ucontext cleanup.
*/
static inline int ib_destroy_usecnt(atomic_t *usecnt,
enum rdma_remove_reason why,
struct ib_uobject *uobj)
{
if (atomic_read(usecnt) && ib_is_destroy_retryable(-EBUSY, why, uobj))
return -EBUSY;
return 0;
}
/**
* ib_modify_qp_is_ok - Check that the supplied attribute mask
* contains all required attributes and no attributes not allowed for

11
include/rdma/uverbs_types.h
View file

@ -93,7 +93,6 @@ struct uverbs_obj_type_class {
struct uverbs_obj_type {
const struct uverbs_obj_type_class * const type_class;
size_t obj_size;
unsigned int destroy_order;
};
/*
@ -152,10 +151,9 @@ extern const struct uverbs_obj_type_class uverbs_fd_class;
#define UVERBS_BUILD_BUG_ON(cond) (sizeof(char[1 - 2 * !!(cond)]) - \
sizeof(char))
#define UVERBS_TYPE_ALLOC_FD(_order, _obj_size, _context_closed, _fops, _name, _flags)\
#define UVERBS_TYPE_ALLOC_FD(_obj_size, _context_closed, _fops, _name, _flags)\
((&((const struct uverbs_obj_fd_type) \
{.type = { \
.destroy_order = _order, \
.type_class = &uverbs_fd_class, \
.obj_size = (_obj_size) + \
UVERBS_BUILD_BUG_ON((_obj_size) < sizeof(struct ib_uobject_file)), \
@ -164,18 +162,17 @@ extern const struct uverbs_obj_type_class uverbs_fd_class;
.fops = _fops, \
.name = _name, \
.flags = _flags}))->type)
#define UVERBS_TYPE_ALLOC_IDR_SZ(_size, _order, _destroy_object) \
#define UVERBS_TYPE_ALLOC_IDR_SZ(_size, _destroy_object) \
((&((const struct uverbs_obj_idr_type) \
{.type = { \
.destroy_order = _order, \
.type_class = &uverbs_idr_class, \
.obj_size = (_size) + \
UVERBS_BUILD_BUG_ON((_size) < \
sizeof(struct ib_uobject)) \
}, \
.destroy_object = _destroy_object,}))->type)
#define UVERBS_TYPE_ALLOC_IDR(_order, _destroy_object) \
UVERBS_TYPE_ALLOC_IDR_SZ(sizeof(struct ib_uobject), _order, \
#define UVERBS_TYPE_ALLOC_IDR(_destroy_object) \
UVERBS_TYPE_ALLOC_IDR_SZ(sizeof(struct ib_uobject), \
_destroy_object)
#endif