linux-kernel - Re: [PATCH v1 02/11] fs/proc/vmcore: replace vmcoredd_mutex by vmcore

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Message-ID: <ZzcVGrUcgNMXPkqw@MiWiFi-R3L-srv>
Date: Fri, 15 Nov 2024 17:32:10 +0800
From: Baoquan He <bhe@...hat.com>
To: David Hildenbrand <david@...hat.com>
Cc: linux-kernel@...r.kernel.org, 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, 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>,
	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: Re: [PATCH v1 02/11] fs/proc/vmcore: replace vmcoredd_mutex by
 vmcore_mutex

On 10/25/24 at 05:11pm, David Hildenbrand wrote:
> Let's use our new mutex instead.

Is there reason vmcoredd_mutex need be replaced and integrated with the
vmcore_mutex? Is it the reason the concurrent opening of vmcore could
happen with the old vmcoredd_mutex?

> 
> Signed-off-by: David Hildenbrand <david@...hat.com>
> ---
>  fs/proc/vmcore.c | 17 ++++++++---------
>  1 file changed, 8 insertions(+), 9 deletions(-)
> 
> diff --git a/fs/proc/vmcore.c b/fs/proc/vmcore.c
> index 110ce193d20f..b91c304463c9 100644
> --- a/fs/proc/vmcore.c
> +++ b/fs/proc/vmcore.c
> @@ -53,7 +53,6 @@ static struct proc_dir_entry *proc_vmcore;
>  #ifdef CONFIG_PROC_VMCORE_DEVICE_DUMP
>  /* Device Dump list and mutex to synchronize access to list */
>  static LIST_HEAD(vmcoredd_list);
> -static DEFINE_MUTEX(vmcoredd_mutex);
>  
>  static bool vmcoredd_disabled;
>  core_param(novmcoredd, vmcoredd_disabled, bool, 0);
> @@ -248,7 +247,7 @@ static int vmcoredd_copy_dumps(struct iov_iter *iter, u64 start, size_t size)
>  	size_t tsz;
>  	char *buf;
>  
> -	mutex_lock(&vmcoredd_mutex);
> +	mutex_lock(&vmcore_mutex);
>  	list_for_each_entry(dump, &vmcoredd_list, list) {
>  		if (start < offset + dump->size) {
>  			tsz = min(offset + (u64)dump->size - start, (u64)size);
> @@ -269,7 +268,7 @@ static int vmcoredd_copy_dumps(struct iov_iter *iter, u64 start, size_t size)
>  	}
>  
>  out_unlock:
> -	mutex_unlock(&vmcoredd_mutex);
> +	mutex_unlock(&vmcore_mutex);
>  	return ret;
>  }
>  
> @@ -283,7 +282,7 @@ static int vmcoredd_mmap_dumps(struct vm_area_struct *vma, unsigned long dst,
>  	size_t tsz;
>  	char *buf;
>  
> -	mutex_lock(&vmcoredd_mutex);
> +	mutex_lock(&vmcore_mutex);
>  	list_for_each_entry(dump, &vmcoredd_list, list) {
>  		if (start < offset + dump->size) {
>  			tsz = min(offset + (u64)dump->size - start, (u64)size);
> @@ -306,7 +305,7 @@ static int vmcoredd_mmap_dumps(struct vm_area_struct *vma, unsigned long dst,
>  	}
>  
>  out_unlock:
> -	mutex_unlock(&vmcoredd_mutex);
> +	mutex_unlock(&vmcore_mutex);
>  	return ret;
>  }
>  #endif /* CONFIG_MMU */
> @@ -1517,9 +1516,9 @@ int vmcore_add_device_dump(struct vmcoredd_data *data)
>  	dump->size = data_size;
>  
>  	/* Add the dump to driver sysfs list */
> -	mutex_lock(&vmcoredd_mutex);
> +	mutex_lock(&vmcore_mutex);
>  	list_add_tail(&dump->list, &vmcoredd_list);
> -	mutex_unlock(&vmcoredd_mutex);
> +	mutex_unlock(&vmcore_mutex);
>  
>  	vmcoredd_update_size(data_size);
>  	return 0;
> @@ -1537,7 +1536,7 @@ EXPORT_SYMBOL(vmcore_add_device_dump);
>  static void vmcore_free_device_dumps(void)
>  {
>  #ifdef CONFIG_PROC_VMCORE_DEVICE_DUMP
> -	mutex_lock(&vmcoredd_mutex);
> +	mutex_lock(&vmcore_mutex);
>  	while (!list_empty(&vmcoredd_list)) {
>  		struct vmcoredd_node *dump;
>  
> @@ -1547,7 +1546,7 @@ static void vmcore_free_device_dumps(void)
>  		vfree(dump->buf);
>  		vfree(dump);
>  	}
> -	mutex_unlock(&vmcoredd_mutex);
> +	mutex_unlock(&vmcore_mutex);
>  #endif /* CONFIG_PROC_VMCORE_DEVICE_DUMP */
>  }
>  
> -- 
> 2.46.1
>