linux-kernel - [PATCH] component: enhance handling of devres group for master

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Date:   Thu,  7 Jun 2018 18:59:18 -0700
From:   bgoswami@...eaurora.org
To:     gregkh@...uxfoundation.org
Cc:     linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        srinivas.kandagatla@...aro.org,
        Banajit Goswami <bgoswami@...eaurora.org>
Subject: [PATCH] component: enhance handling of devres group for master

From: Banajit Goswami <bgoswami@...eaurora.org>

The devres group opened for a master is left open-ended (without
devres_group_close) even after bind() is complete. Similarly, while
releasing the devres resources for master, the most recently opened
devres group is selected, and released without identifying the
targeted group. As the devres group opened before master bind was
never closed, there may have unintended consequences of releasing
devres resources that were allocated after master bind() function
was complete.

Change adds a devres_group_close() after bind() call to master, to
encapsulate the resources allocated during bind, and then use a
group ID to specifically identify the group in release, so that
during master unbind, only the resources that are part of that
specific devres group, are released.

Signed-off-by: Banajit Goswami <bgoswami@...eaurora.org>
---
 drivers/base/component.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/base/component.c b/drivers/base/component.c
index 89b032f..f9ce937 100644
--- a/drivers/base/component.c
+++ b/drivers/base/component.c
@@ -155,17 +155,19 @@ static int try_to_bring_up_master(struct master *master,
 		return 0;
 	}

-	if (!devres_open_group(master->dev, NULL, GFP_KERNEL))
+	if (!devres_open_group(master->dev, master, GFP_KERNEL))
 		return -ENOMEM;

 	/* Found all components */
 	ret = master->ops->bind(master->dev);
 	if (ret < 0) {
-		devres_release_group(master->dev, NULL);
+		devres_release_group(master->dev, master);
 		dev_info(master->dev, "master bind failed: %d\n", ret);
 		return ret;
 	}

+	devres_close_group(master->dev, master);
+
 	master->bound = true;
 	return 1;
 }
@@ -190,7 +192,7 @@ static void take_down_master(struct master *master)
 {
 	if (master->bound) {
 		master->ops->unbind(master->dev);
-		devres_release_group(master->dev, NULL);
+		devres_release_group(master->dev, master);
 		master->bound = false;
 	}
 }
-- 
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