linux-kernel - [PATCH] platform/x86/intel/vsec: Remove a useless mutex

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Message-ID: <ccc08a262304f7f8c2e435349f0f714ebf9acfcd.1730563031.git.christophe.jaillet@wanadoo.fr>
Date: Sat,  2 Nov 2024 16:59:41 +0100
From: Christophe JAILLET <christophe.jaillet@...adoo.fr>
To: srinivas.pandruvada@...ux.intel.com,
	"David E. Box" <david.e.box@...ux.intel.com>,
	Hans de Goede <hdegoede@...hat.com>,
	Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
Cc: linux-kernel@...r.kernel.org,
	kernel-janitors@...r.kernel.org,
	Christophe JAILLET <christophe.jaillet@...adoo.fr>,
	platform-driver-x86@...r.kernel.org
Subject: [PATCH] platform/x86/intel/vsec: Remove a useless mutex

ida_alloc()/ida_free() don't need any mutex, so remove this one.

It was introduced by commit 9a90ea7d3784 ("platform/x86/intel/vsec: Use
mutex for ida_alloc() and ida_free()").

Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
---
See:
https://elixir.bootlin.com/linux/v6.11.2/source/lib/idr.c#L375
https://elixir.bootlin.com/linux/v6.11.2/source/lib/idr.c#L484

Review with care. This patch is clearly the opposite of the one in Fixes
which states that locking IS needed.
IIUC, idr_ functions need locking, but not ida_.

If I'm wrong, could you elaborate why? (because many other places will
need to be fixed and the doc certainly needs updating)
---
 drivers/platform/x86/intel/vsec.c | 6 ------
 1 file changed, 6 deletions(-)

diff --git a/drivers/platform/x86/intel/vsec.c b/drivers/platform/x86/intel/vsec.c
index 7b5cc9993974..9e0f8e38178c 100644
--- a/drivers/platform/x86/intel/vsec.c
+++ b/drivers/platform/x86/intel/vsec.c
@@ -79,17 +79,13 @@ static void intel_vsec_remove_aux(void *data)
 	auxiliary_device_uninit(data);
 }
 
-static DEFINE_MUTEX(vsec_ida_lock);
-
 static void intel_vsec_dev_release(struct device *dev)
 {
 	struct intel_vsec_device *intel_vsec_dev = dev_to_ivdev(dev);
 
 	xa_erase(&auxdev_array, intel_vsec_dev->id);
 
-	mutex_lock(&vsec_ida_lock);
 	ida_free(intel_vsec_dev->ida, intel_vsec_dev->auxdev.id);
-	mutex_unlock(&vsec_ida_lock);
 
 	kfree(intel_vsec_dev->resource);
 	kfree(intel_vsec_dev);
@@ -113,9 +109,7 @@ int intel_vsec_add_aux(struct pci_dev *pdev, struct device *parent,
 		return ret;
 	}
 
-	mutex_lock(&vsec_ida_lock);
 	id = ida_alloc(intel_vsec_dev->ida, GFP_KERNEL);
-	mutex_unlock(&vsec_ida_lock);
 	if (id < 0) {
 		xa_erase(&auxdev_array, intel_vsec_dev->id);
 		kfree(intel_vsec_dev->resource);
-- 
2.47.0