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idr: remove _idr_rc_to_errno() hack

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idr uses -1, IDR_NEED_TO_GROW and IDR_NOMORE_SPACE to communicate
exception conditions internally.  The return value is later translated
to errno values using _idr_rc_to_errno().

This is confusing.  Drop the custom ones and consistently use -EAGAIN
for "tree needs to grow", -ENOMEM for "need more memory" and -ENOSPC for
"ran out of ID space".

Due to the weird memory preloading mechanism, [ra]_get_new*() return
-EAGAIN on memory shortage, so we need to substitute -ENOMEM w/
-EAGAIN on those interface functions.  They'll eventually be cleaned
up and the translations will go away.

This patch doesn't introduce any functional changes.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Tejun Heo 2013-02-27 17:03:53 -08:00 committed by Linus Torvalds
parent 49038ef4fb
commit 12d1b4393e
2 changed files with 23 additions and 18 deletions
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6
include/linux/idr.h
View file

@ -70,12 +70,6 @@ struct idr {
}
#define DEFINE_IDR(name) struct idr name = IDR_INIT(name)
/* Actions to be taken after a call to _idr_sub_alloc */
#define IDR_NEED_TO_GROW -2
#define IDR_NOMORE_SPACE -3
#define _idr_rc_to_errno(rc) ((rc) == -1 ? -EAGAIN : -ENOSPC)
/**
* DOC: idr sync
* idr synchronization (stolen from radix-tree.h)

35
lib/idr.c
View file

@ -133,6 +133,21 @@ int idr_pre_get(struct idr *idp, gfp_t gfp_mask)
}
EXPORT_SYMBOL(idr_pre_get);
/**
* sub_alloc - try to allocate an id without growing the tree depth
* @idp: idr handle
* @starting_id: id to start search at
* @id: pointer to the allocated handle
* @pa: idr_layer[MAX_IDR_LEVEL] used as backtrack buffer
*
* Allocate an id in range [@starting_id, INT_MAX] from @idp without
* growing its depth. Returns
*
* the allocated id >= 0 if successful,
* -EAGAIN if the tree needs to grow for allocation to succeed,
* -ENOSPC if the id space is exhausted,
* -ENOMEM if more idr_layers need to be allocated.
*/
static int sub_alloc(struct idr *idp, int *starting_id, struct idr_layer **pa)
{
int n, m, sh;
@ -161,7 +176,7 @@ static int sub_alloc(struct idr *idp, int *starting_id, struct idr_layer **pa)
/* if already at the top layer, we need to grow */
if (id >= 1 << (idp->layers * IDR_BITS)) {
*starting_id = id;
return IDR_NEED_TO_GROW;
return -EAGAIN;
}
p = pa[l];
BUG_ON(!p);
@ -180,7 +195,7 @@ static int sub_alloc(struct idr *idp, int *starting_id, struct idr_layer **pa)
id = ((id >> sh) ^ n ^ m) << sh;
}
if ((id >= MAX_IDR_BIT) || (id < 0))
return IDR_NOMORE_SPACE;
return -ENOSPC;
if (l == 0)
break;
/*
@ -189,7 +204,7 @@ static int sub_alloc(struct idr *idp, int *starting_id, struct idr_layer **pa)
if (!p->ary[m]) {
new = get_from_free_list(idp);
if (!new)
return -1;
return -ENOMEM;
new->layer = l-1;
rcu_assign_pointer(p->ary[m], new);
p->count++;
@ -215,7 +230,7 @@ static int idr_get_empty_slot(struct idr *idp, int starting_id,
layers = idp->layers;
if (unlikely(!p)) {
if (!(p = get_from_free_list(idp)))
return -1;
return -ENOMEM;
p->layer = 0;
layers = 1;
}
@ -246,7 +261,7 @@ static int idr_get_empty_slot(struct idr *idp, int starting_id,
__move_to_free_list(idp, new);
}
spin_unlock_irqrestore(&idp->lock, flags);
return -1;
return -ENOMEM;
}
new->ary[0] = p;
new->count = 1;
@ -258,7 +273,7 @@ static int idr_get_empty_slot(struct idr *idp, int starting_id,
rcu_assign_pointer(idp->top, p);
idp->layers = layers;
v = sub_alloc(idp, &id, pa);
if (v == IDR_NEED_TO_GROW)
if (v == -EAGAIN)
goto build_up;
return(v);
}
@ -306,12 +321,8 @@ int idr_get_new_above(struct idr *idp, void *ptr, int starting_id, int *id)
int rv;
rv = idr_get_new_above_int(idp, ptr, starting_id);
/*
* This is a cheap hack until the IDR code can be fixed to
* return proper error values.
*/
if (rv < 0)
return _idr_rc_to_errno(rv);
return rv == -ENOMEM ? -EAGAIN : rv;
*id = rv;
return 0;
}
@ -766,7 +777,7 @@ int ida_get_new_above(struct ida *ida, int starting_id, int *p_id)
/* get vacant slot */
t = idr_get_empty_slot(&ida->idr, idr_id, pa);
if (t < 0)
return _idr_rc_to_errno(t);
return t == -ENOMEM ? -EAGAIN : t;
if (t * IDA_BITMAP_BITS >= MAX_IDR_BIT)
return -ENOSPC;