Re: kern/58043: kernel crash in assert_sleepable() in -current, dk(4) driver?

["J. Hannken-Illjes" <hannken%mailbox.org@localhost>]

The following reply was made to PR kern/58043; it has been noted by GNATS.

From: "J. Hannken-Illjes" <hannken%mailbox.org@localhost>
To: gnats-bugs%netbsd.org@localhost
Cc: 
Subject: Re: kern/58043: kernel crash in assert_sleepable() in -current, dk(4)
 driver?
Date: Mon, 18 Mar 2024 10:52:09 +0100

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 Paul,
 
 please try the attached patch -- if it prevents assert_sleepable() to fire
 it is the call to CCD_GETBUF() aka. pool_cache_get(ccd_cache, PR_WAITOK)
 from softint context that has to be fixed.
 
 --
 J. Hannken-Illjes - hannken%mailbox.org@localhost <mailto:hannken%mailbox.org@localhost>
 
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 ccd_defer
 
 Always defer requests to the helper thread so ccdstart() doesn't
 get called from softint anymore.
 
 diff -r 8b8d2498ffd9 -r 2ec4e85f1120 sys/dev/ccd.c
 --- sys/dev/ccd.c
 +++ sys/dev/ccd.c
 @@ -777,17 +777,10 @@ ccdstrategy(struct buf *bp)
  		return;
  	}
  
 -	/* Defer to thread if system is low on memory. */
 +	/* Always defer to thread. */
  	bufq_put(cs->sc_bufq, bp);
 -	if (__predict_false(ccdbackoff(cs))) {
 -		mutex_exit(cs->sc_iolock);
 -#ifdef DEBUG
 - 		if (ccddebug & CCDB_FOLLOW)
 - 			printf("ccdstrategy: holding off on I/O\n");
 -#endif
 -		return;
 -	}
 -	ccdstart(cs);
 +	cv_broadcast(&cs->sc_push);
 +	mutex_exit(cs->sc_iolock);
  }
  
  static void
 
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