RE: Encountered a Null Pointer Problem on the SCSI Layer

[Peter Wong]

Jesper,

     Let's use sd_find_queue() as an example.

     If the array pointed by rscsi_disk has been allocated,
dpnt cannot be null.

     If rscsi_disk has not been allocated, dpnt = &rscsi_disks[target]
may not be null depending on the value of target. Thus, "if (!dpnt)"
is not sufficient anyway.

     You can also look at sd_attach(), in which "if (!dpnt->device)" is
tested, not "if (!dpnt)".

Regards,
Peter

Wai Yee Peter Wong
IBM Linux Technology Center, Performance Analysis
email: [e-mail]

                                                                                                                                       
                      Jesper Juhl                                                                                                      
                      <[e-mail]>             To:       "'Pete Zaitcev '" <[e-mail]>, Peter Wong/Austin/IBM@IBMUS,          
                                                "'[e-mail] '" <[e-mail]>                       
                      01/28/02 05:57 PM        cc:       "'Jens Axboe '" <[e-mail]>                                               
                                               Subject:  RE: Encountered a Null Pointer Problem on the SCSI Layer                      
                                                                                                                                       
                                                                                                                                       
                                                                                                                                       

> -       if (!dpnt)
> +       if (!dpnt->device)
>                 return NULL;    /* No such device */

Maybe I don't understand this right, but shouldn't that be

if (!dpnt || !dpnt->device)
        return NULL;    /* No such device */

?

Best regards,
Jesper Juhl
[e-mail]