linux-kernel - [PATCH 2/4] idr: Add a function idr

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Message-Id: <6d2d9a99d9047a38ae3b8442e537e76c54511c51.1506342921.git.gs051095@gmail.com>
Date:   Mon, 25 Sep 2017 08:56:16 -0400
From:   Gargi Sharma <gs051095@...il.com>
To:     linux-kernel@...r.kernel.org
Cc:     riel@...riel.com, julia.lawall@...6.fr, akpm@...ux-foundation.org,
        mingo@...nel.org, pasha.tatashin@...cle.com, ktkhai@...tuozzo.com,
        oleg@...hat.com, Gargi Sharma <gs051095@...il.com>
Subject: [PATCH 2/4] idr: Add a function idr_get()

idr_get(namespace, id) returns a NULL if id is not present
in the idr tree or returns the pointer to the struct if id is
present in the idr tree. With this function in the idr library,
code for pid allocation can be simplified by calling this function
instead of looking through the pidhash.

Signed-off-by: Gargi Sharma <gs051095@...il.com>
---
 include/linux/idr.h |  1 +
 lib/idr.c           | 11 +++++++++++
 2 files changed, 12 insertions(+)

diff --git a/include/linux/idr.h b/include/linux/idr.h
index 7c3a365..e12b174 100644
--- a/include/linux/idr.h
+++ b/include/linux/idr.h
@@ -135,6 +135,7 @@ int idr_for_each(const struct idr *,
 		 int (*fn)(int id, void *p, void *data), void *data);
 void *idr_get_next(struct idr *, int *nextid);
 void *idr_get_next_ext(struct idr *idr, unsigned long *nextid);
+void *idr_get(struct idr *idr, int *id);
 void *idr_replace(struct idr *, void *, int id);
 void *idr_replace_ext(struct idr *idr, void *ptr, unsigned long id);
 void idr_destroy(struct idr *);
diff --git a/lib/idr.c b/lib/idr.c
index f9adf48..bb76400 100644
--- a/lib/idr.c
+++ b/lib/idr.c
@@ -135,6 +135,17 @@ void *idr_get_next_ext(struct idr *idr, unsigned long *nextid)
 }
 EXPORT_SYMBOL(idr_get_next_ext);
 
+void * idr_get(struct idr *idr, int *id)
+{
+	struct radix_tree_node *node;
+	void __rcu **slot = NULL;
+
+	__radix_tree_lookup(&idr->idr_rt, *id, &node, &slot);
+	if (!slot)
+		return NULL;
+	return node;
+}
+
 /**
  * idr_replace - replace pointer for given id
  * @idr: idr handle
-- 
2.7.4