Re: [PATCH] scsi: mpt3sas: Fix memory allocation failure test in 'mpt3sas_base_attach()'

[Christophe JAILLET]

Le 07/08/2017 Ã 10:25, walter harms a Ãcrit :
> Am 07.08.2017 00:51, schrieb Christophe JAILLET:
> > In the lines above this test, 8 'kzalloc' are performed, but only 7 results
> > are tested.
> >
> > Add the missing one (i.e. '!ioc->port_enable_cmds.reply').
> >
> > Signed-off-by: Christophe JAILLET <christophe.jaillet@xxxxxxxxxx>
> > ---
> >   drivers/scsi/mpt3sas/mpt3sas_base.c | 8 ++++----
> >   1 file changed, 4 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/scsi/mpt3sas/mpt3sas_base.c b/drivers/scsi/mpt3sas/mpt3sas_base.c
> > index 1a5b6e40fb5c..8a44636ab0b5 100644
> > --- a/drivers/scsi/mpt3sas/mpt3sas_base.c
> > +++ b/drivers/scsi/mpt3sas/mpt3sas_base.c
> > @@ -5494,10 +5494,10 @@ mpt3sas_base_attach(struct MPT3SAS_ADAPTER *ioc)
> >   	ioc->ctl_cmds.status = MPT3_CMD_NOT_USED;
> >   	mutex_init(&ioc->ctl_cmds.mutex);
> >   
> > -	if (!ioc->base_cmds.reply || !ioc->transport_cmds.reply ||
> > -	    !ioc->scsih_cmds.reply || !ioc->tm_cmds.reply ||
> > -	    !ioc->config_cmds.reply || !ioc->ctl_cmds.reply ||
> > -	    !ioc->ctl_cmds.sense) {
> > +	if (!ioc->base_cmds.reply || !ioc->port_enable_cmds.reply ||
> > +	    !ioc->transport_cmds.reply || !ioc->scsih_cmds.reply ||
> > +	    !ioc->tm_cmds.reply || !ioc->config_cmds.reply ||
> > +	    !ioc->ctl_cmds.reply || !ioc->ctl_cmds.sense) {
> >   		r = -ENOMEM;
> >   		goto out_free_resources;
> >   	}
>
> obviously it is better to follow the pattern "malloc() , check".
Agreed, but it is also more verbose. Leavig it as-is, is IMHO, good enough.

> Even the programmer lost track.
>
> Bonus points if you malloc the buffers in one step.
Most of the allocation are 'kzalloc(ioc->reply_sz, GFP_KERNEL);', so a 
kcalloc could be used instead.
However, the 'kzalloc(SCSI_SENSE_BUFFERSIZE, GFP_KERNEL);' breaks this 
logic and allocating all at once would lead to spaghetti code for no reason.

Moreover, I don't have any idea how big can be 'ioc->reply_sz', even if 
I guess it should be small.
So allocating all at once, could fail where several steps would work.

So I won't play for the bonus points :).

Best regards.
CJ

> just my 2 cents,
>
> re,
>   wh