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    SubjectRe: [PATCH 1/8] trace: remove deprecated entry->cpu
    On Sun, Feb 08, 2009 at 12:49:56AM -0500, Steven Rostedt wrote:
    > From: Steven Rostedt <srostedt@redhat.com>
    >
    > Impact: fix to prevent developers from using entry->cpu
    >
    > With the new ring buffer infrastructure, the cpu for the entry is
    > implicit with which CPU buffer it is on.
    >
    > The original code use to record the current cpu into the generic
    > entry header, which can be retrieved by entry->cpu. When the
    > ring buffer was introduced, the users were convert to use the
    > the cpu number of which cpu ring buffer was in use (this was passed
    > to the tracers by the iterator: iter->cpu).
    >
    > Unfortunately, the cpu item in the entry structure was never removed.
    > This allowed for developers to use it instead of the proper iter->cpu,
    > unknowingly, using an uninitialized variable. This was not the fault
    > of the developers, since it would seem like the logical place to
    > retrieve the cpu identifier.
    >
    > This patch removes the cpu item from the entry structure and fixes
    > all the users that should have been using iter->cpu.
    >
    > Signed-off-by: Steven Rostedt <srostedt@redhat.com>



    Heh, we have sent the same patch at very few different hours...
    Funny :-)


    > ---
    > kernel/trace/trace.c | 2 +-
    > kernel/trace/trace.h | 1 -
    > kernel/trace/trace_hw_branches.c | 3 +--
    > kernel/trace/trace_output.c | 6 +++---
    > 4 files changed, 5 insertions(+), 7 deletions(-)
    >
    > diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
    > index fd51cf0..bd4d9f8 100644
    > --- a/kernel/trace/trace.c
    > +++ b/kernel/trace/trace.c
    > @@ -1531,7 +1531,7 @@ static enum print_line_t print_bin_fmt(struct trace_iterator *iter)
    >
    > if (trace_flags & TRACE_ITER_CONTEXT_INFO) {
    > SEQ_PUT_FIELD_RET(s, entry->pid);
    > - SEQ_PUT_FIELD_RET(s, entry->cpu);
    > + SEQ_PUT_FIELD_RET(s, iter->cpu);
    > SEQ_PUT_FIELD_RET(s, iter->ts);
    > }
    >
    > diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
    > index f0c7a0f..5efc4c7 100644
    > --- a/kernel/trace/trace.h
    > +++ b/kernel/trace/trace.h
    > @@ -45,7 +45,6 @@ enum trace_type {
    > */
    > struct trace_entry {
    > unsigned char type;
    > - unsigned char cpu;
    > unsigned char flags;
    > unsigned char preempt_count;
    > int pid;
    > diff --git a/kernel/trace/trace_hw_branches.c b/kernel/trace/trace_hw_branches.c
    > index fff3545..549238a 100644
    > --- a/kernel/trace/trace_hw_branches.c
    > +++ b/kernel/trace/trace_hw_branches.c
    > @@ -159,7 +159,7 @@ static enum print_line_t bts_trace_print_line(struct trace_iterator *iter)
    > trace_assign_type(it, entry);
    >
    > if (entry->type == TRACE_HW_BRANCHES) {
    > - if (trace_seq_printf(seq, "%4d ", entry->cpu) &&
    > + if (trace_seq_printf(seq, "%4d ", iter->cpu) &&
    > seq_print_ip_sym(seq, it->to, symflags) &&
    > trace_seq_printf(seq, "\t <- ") &&
    > seq_print_ip_sym(seq, it->from, symflags) &&
    > @@ -195,7 +195,6 @@ void trace_hw_branch(u64 from, u64 to)
    > entry = ring_buffer_event_data(event);
    > tracing_generic_entry_update(&entry->ent, 0, from);
    > entry->ent.type = TRACE_HW_BRANCHES;
    > - entry->ent.cpu = cpu;
    > entry->from = from;
    > entry->to = to;
    > ring_buffer_unlock_commit(tr->buffer, event, irq2);
    > diff --git a/kernel/trace/trace_output.c b/kernel/trace/trace_output.c
    > index b7380ee..463a310 100644
    > --- a/kernel/trace/trace_output.c
    > +++ b/kernel/trace/trace_output.c
    > @@ -333,7 +333,7 @@ int trace_print_context(struct trace_iterator *iter)
    > unsigned long secs = (unsigned long)t;
    >
    > return trace_seq_printf(s, "%16s-%-5d [%03d] %5lu.%06lu: ",
    > - comm, entry->pid, entry->cpu, secs, usec_rem);
    > + comm, entry->pid, iter->cpu, secs, usec_rem);
    > }
    >
    > int trace_print_lat_context(struct trace_iterator *iter)
    > @@ -356,7 +356,7 @@ int trace_print_lat_context(struct trace_iterator *iter)
    > char *comm = trace_find_cmdline(entry->pid);
    > ret = trace_seq_printf(s, "%16s %5d %3d %d %08x %08lx [%08lx]"
    > " %ld.%03ldms (+%ld.%03ldms): ", comm,
    > - entry->pid, entry->cpu, entry->flags,
    > + entry->pid, iter->cpu, entry->flags,
    > entry->preempt_count, iter->idx,
    > ns2usecs(iter->ts),
    > abs_usecs / USEC_PER_MSEC,
    > @@ -364,7 +364,7 @@ int trace_print_lat_context(struct trace_iterator *iter)
    > rel_usecs / USEC_PER_MSEC,
    > rel_usecs % USEC_PER_MSEC);
    > } else {
    > - ret = lat_print_generic(s, entry, entry->cpu);
    > + ret = lat_print_generic(s, entry, iter->cpu);
    > if (ret)
    > ret = lat_print_timestamp(s, abs_usecs, rel_usecs);
    > }
    > --
    > 1.5.6.5
    >
    > --



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