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Date: Sat, 2 Feb 2013 17:20:04 -0800
From: Tejun Heo <tj@...nel.org>
To: akpm@...ux-foundation.org
Cc: linux-kernel@...r.kernel.org, rusty@...tcorp.com.au,
bfields@...ldses.org, skinsbursky@...allels.com,
ebiederm@...ssion.com, jmorris@...ei.org, axboe@...nel.dk,
Tejun Heo <tj@...nel.org>
Subject: [PATCH 03/62] idr: remove _idr_rc_to_errno() hack
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@...nel.org>
---
include/linux/idr.h | 6 ------
lib/idr.c | 35 +++++++++++++++++++++++------------
2 files changed, 23 insertions(+), 18 deletions(-)
diff --git a/include/linux/idr.h b/include/linux/idr.h
index 7c0700c..92e84f7 100644
--- a/include/linux/idr.h
+++ b/include/linux/idr.h
@@ -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)
diff --git a/lib/idr.c b/lib/idr.c
index 282841b..bde6eec 100644
--- a/lib/idr.c
+++ b/lib/idr.c
@@ -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 @@ build_up:
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 @@ build_up:
__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 @@ build_up:
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;
--
1.8.1
--
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