On 03/22/2012 01:30 AM, Dan Carpenter wrote:
> Hello Tim Bird,
>
> This is a semi-automatic email about new static checker warnings.
>
> The patch 3492c71d374c: "kdb: Avoid using dbg_io_ops until it is
> initialized" from Sep 21, 2011, leads to the following Smatch
> complaint:
>
> kernel/debug/kdb/kdb_io.c:746 vkdb_printf()
> error: we previously assumed 'dbg_io_ops' could be null (see line 692)
>
> kernel/debug/kdb/kdb_io.c
> 691 } else {
> 692 if (dbg_io_ops && !dbg_io_ops->is_console) {
> ^^^^^^^^^^
> New check.
>
> 693 len = strlen(kdb_buffer);
> 694 cp = kdb_buffer;
> 695 while (len--) {
> 696 dbg_io_ops->write_char(*cp);
> 697 cp++;
> 698 }
> 699 }
>
> [snip]
>
> 742
> 743 kdb_input_flush();
> 744 c = console_drivers;
> 745
> 746 if (!dbg_io_ops->is_console) {
> ^^^^^^^^^^
> Old dereference. Should we check here as well?
I had the same question when I reviewed and tested this code. This section of
code is protected by the kdb pager block, where dbg_io_ops cannot be null.
Should I be adding a comment to that effect, or just pay the price for the null
check to squelch the warning?
Jason.
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