linux-kernel - [PATCH v1 01/11] fs/proc/vmcore: convert vmcore_cb_lock into vmcore

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Message-ID: <20241025151134.1275575-2-david@redhat.com>
Date: Fri, 25 Oct 2024 17:11:23 +0200
From: David Hildenbrand <david@...hat.com>
To: linux-kernel@...r.kernel.org
Cc: linux-mm@...ck.org,
	linux-s390@...r.kernel.org,
	virtualization@...ts.linux.dev,
	kvm@...r.kernel.org,
	linux-fsdevel@...r.kernel.org,
	kexec@...ts.infradead.org,
	David Hildenbrand <david@...hat.com>,
	Heiko Carstens <hca@...ux.ibm.com>,
	Vasily Gorbik <gor@...ux.ibm.com>,
	Alexander Gordeev <agordeev@...ux.ibm.com>,
	Christian Borntraeger <borntraeger@...ux.ibm.com>,
	Sven Schnelle <svens@...ux.ibm.com>,
	"Michael S. Tsirkin" <mst@...hat.com>,
	Jason Wang <jasowang@...hat.com>,
	Xuan Zhuo <xuanzhuo@...ux.alibaba.com>,
	Eugenio Pérez <eperezma@...hat.com>,
	Baoquan He <bhe@...hat.com>,
	Vivek Goyal <vgoyal@...hat.com>,
	Dave Young <dyoung@...hat.com>,
	Thomas Huth <thuth@...hat.com>,
	Cornelia Huck <cohuck@...hat.com>,
	Janosch Frank <frankja@...ux.ibm.com>,
	Claudio Imbrenda <imbrenda@...ux.ibm.com>,
	Eric Farman <farman@...ux.ibm.com>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: [PATCH v1 01/11] fs/proc/vmcore: convert vmcore_cb_lock into vmcore_mutex

We want to protect vmcore modifications from concurrent opening of
the vmcore, and also serialize vmcore modiciations. Let's convert the
spinlock into a mutex, because some of the operations we'll be
protecting might sleep (e.g., memory allocations) and might take a bit
longer.

Signed-off-by: David Hildenbrand <david@...hat.com>
---
 fs/proc/vmcore.c | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c
index b52d85f8ad59..110ce193d20f 100644
--- a/fs/proc/vmcore.c
+++ b/fs/proc/vmcore.c
@@ -62,7 +62,8 @@ core_param(novmcoredd, vmcoredd_disabled, bool, 0);
 /* Device Dump Size */
 static size_t vmcoredd_orig_sz;
 
-static DEFINE_SPINLOCK(vmcore_cb_lock);
+static DEFINE_MUTEX(vmcore_mutex);
+
 DEFINE_STATIC_SRCU(vmcore_cb_srcu);
 /* List of registered vmcore callbacks. */
 static LIST_HEAD(vmcore_cb_list);
@@ -72,7 +73,7 @@ static bool vmcore_opened;
 void register_vmcore_cb(struct vmcore_cb *cb)
 {
 	INIT_LIST_HEAD(&cb->next);
-	spin_lock(&vmcore_cb_lock);
+	mutex_lock(&vmcore_mutex);
 	list_add_tail(&cb->next, &vmcore_cb_list);
 	/*
 	 * Registering a vmcore callback after the vmcore was opened is
@@ -80,13 +81,13 @@ void register_vmcore_cb(struct vmcore_cb *cb)
 	 */
 	if (vmcore_opened)
 		pr_warn_once("Unexpected vmcore callback registration\n");
-	spin_unlock(&vmcore_cb_lock);
+	mutex_unlock(&vmcore_mutex);
 }
 EXPORT_SYMBOL_GPL(register_vmcore_cb);
 
 void unregister_vmcore_cb(struct vmcore_cb *cb)
 {
-	spin_lock(&vmcore_cb_lock);
+	mutex_lock(&vmcore_mutex);
 	list_del_rcu(&cb->next);
 	/*
 	 * Unregistering a vmcore callback after the vmcore was opened is
@@ -95,7 +96,7 @@ void unregister_vmcore_cb(struct vmcore_cb *cb)
 	 */
 	if (vmcore_opened)
 		pr_warn_once("Unexpected vmcore callback unregistration\n");
-	spin_unlock(&vmcore_cb_lock);
+	mutex_unlock(&vmcore_mutex);
 
 	synchronize_srcu(&vmcore_cb_srcu);
 }
@@ -120,9 +121,9 @@ static bool pfn_is_ram(unsigned long pfn)
 
 static int open_vmcore(struct inode *inode, struct file *file)
 {
-	spin_lock(&vmcore_cb_lock);
+	mutex_lock(&vmcore_mutex);
 	vmcore_opened = true;
-	spin_unlock(&vmcore_cb_lock);
+	mutex_unlock(&vmcore_mutex);
 
 	return 0;
 }
-- 
2.46.1