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* [PATCH] scsi: fix missing lock protection
@ 2025-02-19  8:11 Chaohai Chen
  2025-02-19 18:06 ` Bart Van Assche
  0 siblings, 1 reply; 3+ messages in thread
From: Chaohai Chen @ 2025-02-19  8:11 UTC (permalink / raw)
  To: martin.petersen; +Cc: James.Bottomley, linux-scsi, linux-kernel, Chaohai Chen

async_scan_lock is designed to protect the scanning_hosts list,
but there is no protection here.

Signed-off-by: Chaohai Chen <wdhh66@163.com>
---
 drivers/scsi/scsi_scan.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
index 087fcbfc9aaa..9a90e6ba5603 100644
--- a/drivers/scsi/scsi_scan.c
+++ b/drivers/scsi/scsi_scan.c
@@ -151,8 +151,12 @@ int scsi_complete_async_scans(void)
 	struct async_scan_data *data;
 
 	do {
-		if (list_empty(&scanning_hosts))
+		spin_lock(&async_scan_lock);
+		if (list_empty(&scanning_hosts)) {
+			spin_unlock(&async_scan_lock);
 			return 0;
+		}
+		spin_unlock(&async_scan_lock);
 		/* If we can't get memory immediately, that's OK.  Just
 		 * sleep a little.  Even if we never get memory, the async
 		 * scans will finish eventually.
-- 
2.34.1


^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: [PATCH] scsi: fix missing lock protection
  2025-02-19  8:11 [PATCH] scsi: fix missing lock protection Chaohai Chen
@ 2025-02-19 18:06 ` Bart Van Assche
  2025-02-20  3:01   ` Chaohai Chen
  0 siblings, 1 reply; 3+ messages in thread
From: Bart Van Assche @ 2025-02-19 18:06 UTC (permalink / raw)
  To: Chaohai Chen, martin.petersen; +Cc: James.Bottomley, linux-scsi, linux-kernel

On 2/19/25 12:11 AM, Chaohai Chen wrote:
> async_scan_lock is designed to protect the scanning_hosts list,
> but there is no protection here.
> 
> Signed-off-by: Chaohai Chen <wdhh66@163.com>
> ---
>   drivers/scsi/scsi_scan.c | 6 +++++-
>   1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
> index 087fcbfc9aaa..9a90e6ba5603 100644
> --- a/drivers/scsi/scsi_scan.c
> +++ b/drivers/scsi/scsi_scan.c
> @@ -151,8 +151,12 @@ int scsi_complete_async_scans(void)
>   	struct async_scan_data *data;
>   
>   	do {
> -		if (list_empty(&scanning_hosts))
> +		spin_lock(&async_scan_lock);
> +		if (list_empty(&scanning_hosts)) {
> +			spin_unlock(&async_scan_lock);
>   			return 0;
> +		}
> +		spin_unlock(&async_scan_lock);
>   		/* If we can't get memory immediately, that's OK.  Just
>   		 * sleep a little.  Even if we never get memory, the async
>   		 * scans will finish eventually.

Has it been considered to use scoped_guard() as in the untested patch
below?

Thanks,

Bart.


diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
index 087fcbfc9aaa..efc90571ab47 100644
--- a/drivers/scsi/scsi_scan.c
+++ b/drivers/scsi/scsi_scan.c
@@ -151,8 +151,9 @@ int scsi_complete_async_scans(void)
  	struct async_scan_data *data;

  	do {
-		if (list_empty(&scanning_hosts))
-			return 0;
+		scoped_guard(spinlock, &async_scan_lock)
+			if (list_empty(&scanning_hosts))
+				return 0;
  		/* If we can't get memory immediately, that's OK.  Just
  		 * sleep a little.  Even if we never get memory, the async
  		 * scans will finish eventually.


^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: [PATCH] scsi: fix missing lock protection
  2025-02-19 18:06 ` Bart Van Assche
@ 2025-02-20  3:01   ` Chaohai Chen
  0 siblings, 0 replies; 3+ messages in thread
From: Chaohai Chen @ 2025-02-20  3:01 UTC (permalink / raw)
  To: wdhh66, martin.petersen
  Cc: James.Bottomley, linux-scsi, linux-kernel, Bart Van Assche

From: Bart Van Assche <bvanassche@acm.org>

On 2/19/25 12:11 AM, Chaohai Chen wrote:
>> async_scan_lock is designed to protect the scanning_hosts list,
>> but there is no protection here.
>> 
>> Signed-off-by: Chaohai Chen <wdhh66@163.com>
>> ---
>>   drivers/scsi/scsi_scan.c | 6 +++++-
>>   1 file changed, 5 insertions(+), 1 deletion(-)
>> 
>> diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
>> index 087fcbfc9aaa..9a90e6ba5603 100644
>> --- a/drivers/scsi/scsi_scan.c
>> +++ b/drivers/scsi/scsi_scan.c
>> @@ -151,8 +151,12 @@ int scsi_complete_async_scans(void)
>>   	struct async_scan_data *data;
>>   
>>   	do {
>> -		if (list_empty(&scanning_hosts))
>> +		spin_lock(&async_scan_lock);
>> +		if (list_empty(&scanning_hosts)) {
>> +			spin_unlock(&async_scan_lock);
>>   			return 0;
>> +		}
>> +		spin_unlock(&async_scan_lock);
>>   		/* If we can't get memory immediately, that's OK.  Just
>>   		 * sleep a little.  Even if we never get memory, the async
>>   		 * scans will finish eventually.
>
>Has it been considered to use scoped_guard() as in the untested patch
>below?
>
>Thanks,
>
>Bart.
>
>
>diff --git a/drivers/scsi/scsi_scan.c b/drivers/scsi/scsi_scan.c
>index 087fcbfc9aaa..efc90571ab47 100644
>--- a/drivers/scsi/scsi_scan.c
>+++ b/drivers/scsi/scsi_scan.c
>@@ -151,8 +151,9 @@ int scsi_complete_async_scans(void)
>  	struct async_scan_data *data;
>
>  	do {
>-		if (list_empty(&scanning_hosts))
>-			return 0;
>+		scoped_guard(spinlock, &async_scan_lock)
>+			if (list_empty(&scanning_hosts))
>+				return 0;
>  		/* If we can't get memory immediately, that's OK.  Just
>  		 * sleep a little.  Even if we never get memory, the async
>  		 * scans will finish eventually.
>
>

Of course, it looks nice, thanks.

Chaohai


^ permalink raw reply	[flat|nested] 3+ messages in thread

end of thread, other threads:[~2025-02-20  3:02 UTC | newest]

Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
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2025-02-19  8:11 [PATCH] scsi: fix missing lock protection Chaohai Chen
2025-02-19 18:06 ` Bart Van Assche
2025-02-20  3:01   ` Chaohai Chen

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