perf session: Fix infinite loop in __perf_session__process_events

In this if statement:

if (head + event->header.size >= mmap_size) {
if (mmaps[map_idx]) {
munmap(mmaps[map_idx], mmap_size);
mmaps[map_idx] = NULL;
}

page_offset = page_size * (head / page_size);
file_offset += page_offset;
head -= page_offset;
goto remap;
}

With, for instance, these values:

head=2992
event->header.size=48
mmap_size=3040

We end up endlessly looping back to remap. Off by one.

Problem introduced in 55b4462.

Reported-by: Linus Torvalds <[e-mail]>
Reported-by: Ingo Molnar <[e-mail]>
Reported-by: David Ahern <[e-mail]>
Bisected-by: David Ahern <[e-mail]>
Tested-by: David Ahern <[e-mail]>
Cc: David Ahern <[e-mail]>
Cc: Frederic Weisbecker <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: Mike Galbraith <[e-mail]>
Cc: Paul Mackerras <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Cc: Stephane Eranian <[e-mail]>
Cc: Thomas Gleixner <[e-mail]>
Cc: Tom Zanussi <[e-mail]>
LKML-Reference: <new-submission>
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/util/session.c

···
 	if (size == 0)
 		size = 8;
 
-	if (head + event->header.size >= mmap_size) {
+	if (head + event->header.size > mmap_size) {
 		if (mmaps[map_idx]) {
 			munmap(mmaps[map_idx], mmap_size);
 			mmaps[map_idx] = NULL;