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tracing: Don't use p->len field to determine output in __print_*() functions

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If more than one __print_*() function is used in a tracepoint
(__print_flags(), __print_symbols(), etc), then the temp seq buffer will
not be zero on entry. Using the temp seq buffer's length to know if
data has been printed or not in the current function is incorrect and
may produce incorrect results.

Currently, no in-tree tracepoint causes this bug, but new ones may
be created.

Cc: Andrew Vagin <avagin@openvz.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt 2012-02-20 20:37:32 -05:00 committed by Steven Rostedt
parent e404b321db
commit 5b34926114
1 changed files with 3 additions and 3 deletions
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6
kernel/trace/trace_output.c
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@ -319,7 +319,7 @@ ftrace_print_flags_seq(struct trace_seq *p, const char *delim,
/* check for left over flags */
if (flags) {
if (p->len && delim)
if (!first && delim)
trace_seq_puts(p, delim);
trace_seq_printf(p, "0x%lx", flags);
}
@ -346,7 +346,7 @@ ftrace_print_symbols_seq(struct trace_seq *p, unsigned long val,
break;
}
if (!p->len)
if (ret == (const char *)(p->buffer + p->len))
trace_seq_printf(p, "0x%lx", val);
trace_seq_putc(p, 0);
@ -372,7 +372,7 @@ ftrace_print_symbols_seq_u64(struct trace_seq *p, unsigned long long val,
break;
}
if (!p->len)
if (ret == (const char *)(p->buffer + p->len))
trace_seq_printf(p, "0x%llx", val);
trace_seq_putc(p, 0);