linux-kernel - [PATCH v2] drm/vc4: replace idr_init() by idr_init

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Message-ID: <20201105202135.GA145111@localhost>
Date:   Fri, 6 Nov 2020 01:51:35 +0530
From:   Deepak R Varma <mh12gx2825@...il.com>
To:     Eric Anholt <eric@...olt.net>, David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Cc:     mh12gx2825@...il.com, Maxime Ripard <mripard@...nel.org>,
        Maxime Ripard <maxime@...no.tech>
Subject: [PATCH v2] drm/vc4: replace idr_init() by idr_init_base()

idr_init() uses base 0 which is an invalid identifier for this driver.
The idr_alloc for this driver uses VC4_PERFMONID_MIN as start value for
ID range and it is #defined to 1. The new function idr_init_base allows
IDR to set the ID lookup from base 1. This avoids all lookups that
otherwise starts from 0 since 0 is always unused / available.

References: commit 6ce711f27500 ("idr: Make 1-based IDRs more efficient")

Signed-off-by: Deepak R Varma <mh12gx2825@...il.com>
---
Changes since v1:
   - Change suggested by Eric Anholt
     1. Use VC4_PERFMONID_MIN instead of magic number 1

 drivers/gpu/drm/vc4/vc4_perfmon.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/vc4/vc4_perfmon.c b/drivers/gpu/drm/vc4/vc4_perfmon.c
index f4aa75efd16b..18abc06335c1 100644
--- a/drivers/gpu/drm/vc4/vc4_perfmon.c
+++ b/drivers/gpu/drm/vc4/vc4_perfmon.c
@@ -77,7 +77,7 @@ struct vc4_perfmon *vc4_perfmon_find(struct vc4_file *vc4file, int id)
 void vc4_perfmon_open_file(struct vc4_file *vc4file)
 {
 	mutex_init(&vc4file->perfmon.lock);
-	idr_init(&vc4file->perfmon.idr);
+	idr_init_base(&vc4file->perfmon.idr, VC4_PERFMONID_MIN);
 }
 
 static int vc4_perfmon_idr_del(int id, void *elem, void *data)
-- 
2.25.1