kern/130735: [patch] pass M_NOWAIT to the malloc() call inside cdreaddvdstructure()

[Eygene Ryabinkin]

The following reply was made to PR kern/130735; it has been noted by GNATS.

From: Eygene Ryabinkin <rea-fbsd at codelabs.ru>
To: Jaakko Heinonen <jh at saunalahti.fi>
Cc: bug-followup at FreeBSD.org
Subject: Re: kern/130735: [patch] pass M_NOWAIT to the malloc() call inside
	cdreaddvdstructure()
Date: Mon, 19 Jan 2009 22:25:28 +0300

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 Jakko, good day.
 
 Mon, Jan 19, 2009 at 05:06:47PM +0200, Jaakko Heinonen wrote:
 > On 2009-01-19, Eygene Ryabinkin wrote:
 > > --- a/sys/cam/scsi/scsi_cd.c
 > > +++ b/sys/cam/scsi/scsi_cd.c
 > > @@ -4063,7 +4063,7 @@ cdreaddvdstructure(struct cam_periph *periph, struct dvd_struct *dvdstruct)
 > >  	}
 > >  
 > >  	if (length != 0) {
 > > -		databuf = malloc(length, M_DEVBUF, M_WAITOK | M_ZERO);
 > > +		databuf = malloc(length, M_DEVBUF, M_NOWAIT | M_ZERO);
 > >  	} else
 > >  		databuf = NULL;
 > 
 > This change doesn't look correct. If you use M_NOWAIT malloc(9) can fail
 > and return NULL.
 
 Good catch -- I wasn't aware of it.  The attached patch should be
 slightly better.
 -- 
 Eygene
  _                ___       _.--.   #
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  /  ' `         ,       __.--'      #  to read the on-line manual
  )/' _/     \   `-_,   /            #  while single-stepping the kernel.
  `-'" `"\_  ,_.-;_.-\_ ',  fsc/as   #
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     {_.-``-'         {_/            #
 
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 --- sys/cam/scsi/scsi_cd.c.orig	2007-07-21 22:07:45.000000000 +0400
 +++ sys/cam/scsi/scsi_cd.c	2009-01-19 22:19:18.000000000 +0300
 @@ -4063,7 +4063,11 @@
  	}
  
  	if (length != 0) {
 -		databuf = malloc(length, M_DEVBUF, M_WAITOK | M_ZERO);
 +		databuf = malloc(length, M_DEVBUF, M_NOWAIT | M_ZERO);
 +		if (databuf == NULL) {
 +			error = ENOMEM;
 +			goto bailout;
 +		}
  	} else
  		databuf = NULL;
  
 
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