Re: [PATCH v2 6/7] scsi: scsi_debug: Improve lock context annotations

[Bart Van Assche <bvanassche@acm.org>]

On 9/25/26 2:15 AM, John Garry wrote:
> On 9/24/26 23:54, Bart Van Assche wrote:
>>   static inline void
>>   sdeb_data_lock(struct sdeb_store_info *sip, bool atomic)
>> +    __acquires(&sip->macc_data_lck)
> 
> Is this proper?
> 
> sdeb_data_lock() can call sdeb_data_read_lock(), and 
> sdeb_data_read_lock() uses __acquires_shared().
> 
> Indeed, but functions which sdeb_data_lock() call already have lock 
> context annotations, so I wonder if this annotation is even needed.
> 
>> +    __context_unsafe(/*conditional locking*/)

Hi John,

Some annotations are needed. If I remove both annotations Clang reports
the following warnings:

drivers/scsi/scsi_debug.c:4168:3: error: rwlock 'sip->macc_data_lck' is 
acquired exclusively and shared in the same scope 
[-Werror,-Wthread-safety-analysis]
  4168 |                 sdeb_data_write_lock(sip);
       |                 ^
drivers/scsi/scsi_debug.c:4170:3: note: the other acquisition of rwlock 
'sip->macc_data_lck' is here
  4170 |                 sdeb_data_read_lock(sip);
       |                 ^
drivers/scsi/scsi_debug.c:4171:1: error: rwlock 'sip->macc_data_lck' is 
still held at the end of function [-Werror,-Wthread-safety-analysis]
  4171 | }
       | ^
drivers/scsi/scsi_debug.c:4168:3: note: rwlock acquired here
  4168 |                 sdeb_data_write_lock(sip);
       |                 ^
drivers/scsi/scsi_debug.c:4177:3: error: releasing rwlock 
'sip->macc_data_lck' that was not held [-Werror,-Wthread-safety-analysis]
  4177 |                 sdeb_data_write_unlock(sip);
       |                 ^
drivers/scsi/scsi_debug.c:4179:3: error: releasing rwlock 
'sip->macc_data_lck' that was not held [-Werror,-Wthread-safety-analysis]
  4179 |                 sdeb_data_read_unlock(sip);
       |                 ^

Thanks,

Bart.