The patch titled
Subject: idr: introduce idr_alloc_cyclic()
has been added to the -mm tree. Its filename is
idr-introduce-idr_alloc_cyclic.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Jeff Layton <jlayton@xxxxxxxxxx>
Subject: idr: introduce idr_alloc_cyclic()
As Tejun points out, there are several users of the IDR facility that
attempt to use it in a cyclic fashion. These users are likely to see
-ENOSPC errors after the counter wraps one or more times however.
This patchset adds a new idr_alloc_cyclic routine and converts several of
these users to it. Many of these users are in obscure parts of the
kernel, and I don't have a good way to test some of them. The change is
pretty straightforward though, so hopefully it won't be an issue.
There is one other cyclic user of idr_alloc that I didn't touch in
ipc/util.c. That one is doing some strange stuff that I didn't quite
understand, but it looks like it should probably be converted later
somehow.
This patch:
Thus spake Tejun Heo:
Ooh, BTW, the cyclic allocation is broken. It's prone to -ENOSPC
after the first wraparound. There are several cyclic users in the
kernel and I think it probably would be best to implement cyclic
support in idr.
This patch does that by adding new idr_alloc_cyclic function that such
users in the kernel can use. With this, there's no need for a caller to
keep track of the last value used as that's now tracked internally. This
should prevent the ENOSPC problems that can hit when the "last allocated"
counter exceeds INT_MAX.
Later patches will convert existing cyclic users to the new interface.
Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
Reviewed-by: Tejun Heo <tj@xxxxxxxxxx>
Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
Cc: "J. Bruce Fields" <bfields@xxxxxxxxxxxx>
Cc: Eric Paris <eparis@xxxxxxxxxxxxxx>
Cc: Jack Morgenstein <jackm@xxxxxxxxxxxxxxxxxx>
Cc: John McCutchan <john@xxxxxxxxxxxxxxxxx>
Cc: Neil Horman <nhorman@xxxxxxxxxxxxx>
Cc: Or Gerlitz <ogerlitz@xxxxxxxxxxxx>
Cc: Robert Love <rlove@xxxxxxxxx>
Cc: Roland Dreier <roland@xxxxxxxxxxxxxxx>
Cc: Sridhar Samudrala <sri@xxxxxxxxxx>
Cc: Steve Wise <swise@xxxxxxxxxxxxxxxxxxxxx>
Cc: Tom Tucker <tom@xxxxxxxxxxxxxxxxxxxxx>
Cc: Vlad Yasevich <vyasevich@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/idr.h | 2 ++
lib/idr.c | 27 +++++++++++++++++++++++++++
2 files changed, 29 insertions(+)
diff -puN include/linux/idr.h~idr-introduce-idr_alloc_cyclic include/linux/idr.h
--- a/include/linux/idr.h~idr-introduce-idr_alloc_cyclic
+++ a/include/linux/idr.h
@@ -42,6 +42,7 @@ struct idr {
struct idr_layer *id_free;
int layers; /* only valid w/o concurrent changes */
int id_free_cnt;
+ int cur; /* current pos for cyclic allocation */
spinlock_t lock;
};
@@ -75,6 +76,7 @@ struct idr {
void *idr_find_slowpath(struct idr *idp, int id);
void idr_preload(gfp_t gfp_mask);
int idr_alloc(struct idr *idp, void *ptr, int start, int end, gfp_t gfp_mask);
+int idr_alloc_cyclic(struct idr *idr, void *ptr, int start, int end, gfp_t gfp_mask);
int idr_for_each(struct idr *idp,
int (*fn)(int id, void *p, void *data), void *data);
void *idr_get_next(struct idr *idp, int *nextid);
diff -puN lib/idr.c~idr-introduce-idr_alloc_cyclic lib/idr.c
--- a/lib/idr.c~idr-introduce-idr_alloc_cyclic
+++ a/lib/idr.c
@@ -495,6 +495,33 @@ int idr_alloc(struct idr *idr, void *ptr
}
EXPORT_SYMBOL_GPL(idr_alloc);
+/**
+ * idr_alloc_cyclic - allocate new idr entry in a cyclical fashion
+ * @idr: the (initialized) idr
+ * @ptr: pointer to be associated with the new id
+ * @start: the minimum id (inclusive)
+ * @end: the maximum id (exclusive, <= 0 for max)
+ * @gfp_mask: memory allocation flags
+ *
+ * Essentially the same as idr_alloc, but prefers to allocate progressively
+ * higher ids if it can. If the "cur" counter wraps, then it will start again
+ * at the "start" end of the range and allocate one that has already been used.
+ */
+int idr_alloc_cyclic(struct idr *idr, void *ptr, int start, int end,
+ gfp_t gfp_mask)
+{
+ int id;
+
+ id = idr_alloc(idr, ptr, max(start, idr->cur), end, gfp_mask);
+ if (id == -ENOSPC)
+ id = idr_alloc(idr, ptr, start, end, gfp_mask);
+
+ if (likely(id >= 0))
+ idr->cur = id + 1;
+ return id;
+}
+EXPORT_SYMBOL(idr_alloc_cyclic);
+
static void idr_remove_warning(int id)
{
printk(KERN_WARNING
_
Patches currently in -mm which might be from jlayton@xxxxxxxxxx are
origin.patch
linux-next.patch
idr-introduce-idr_alloc_cyclic.patch
drivers-infiniband-hw-amso1100-convert-to-using-idr_alloc_cyclic.patch
drivers-infiniband-hw-mlx4-convert-to-using-idr_alloc_cyclic.patch
nfsd-convert-nfs4_alloc_stid-to-use-idr_alloc_cyclic.patch
inotify-convert-inotify_add_to_idr-to-use-idr_alloc_cyclic.patch
sctp-convert-sctp_assoc_set_id-to-use-idr_alloc_cyclic.patch
--
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
