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x86: UV BAU: Avoid NULL pointer reference in ptc_seq_show 

In init_per_cpu(), when get_cpu_topology() fails, init_per_cpu_tunables()
is not called afterwards. This means that bau_control->statp is NULL.
If a user then reads /proc/sgi_uv/ptc_statistics ptc_seq_show() references
a NULL pointer. Therefore, since uv_bau_init calls set_bau_off when
init_per_cpu() fails, we add code that detects when the bau is off in
ptc_seq_show() to avoid referencing a NULL pointer.

Signed-off-by: James Custer <jcuster@sgi.com>
Cc: Russ Anderson <rja@sgi.com>
Link: http://lkml.kernel.org/r/1414952199-185319-2-git-send-email-jcuster@sgi.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
James Custer 2014-11-02 12:16:39 -06:00 committed by Thomas Gleixner
parent 0df1f2487d
commit fa2a79ce6a
1 changed files with 4 additions and 0 deletions
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4
arch/x86/platform/uv/tlb_uv.c
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@ -1384,6 +1384,10 @@ static int ptc_seq_show(struct seq_file *file, void *data)
}
if (cpu < num_possible_cpus() && cpu_online(cpu)) {
bcp = &per_cpu(bau_control, cpu);
if (bcp->nobau) {
seq_printf(file, "cpu %d bau disabled\n", cpu);
return 0;
}
stat = bcp->statp;
/* source side statistics */
seq_printf(file,