1. 22 Mar, 2016 1 commit
    • Steven Rostedt (Red Hat)'s avatar
      tracing: Fix trace_printk() to print when not using bprintk() · 3debb0a9
      Steven Rostedt (Red Hat) authored
      The trace_printk() code will allocate extra buffers if the compile detects
      that a trace_printk() is used. To do this, the format of the trace_printk()
      is saved to the __trace_printk_fmt section, and if that section is bigger
      than zero, the buffers are allocated (along with a message that this has
      happened).
      
      If trace_printk() uses a format that is not a constant, and thus something
      not guaranteed to be around when the print happens, the compiler optimizes
      the fmt out, as it is not used, and the __trace_printk_fmt section is not
      filled. This means the kernel will not allocate the special buffers needed
      for the trace_printk() and the trace_printk() will not write anything to the
      tracing buffer.
      
      Adding a "__used" to the variable in the __trace_printk_fmt section will
      keep it around, even though it is set to NULL. This will keep the string
      from being printed in the debugfs/tracing/printk_formats section as it is
      not needed.
      Reported-by: default avatarVlastimil Babka <vbabka@suse.cz>
      Fixes: 07d777fe "tracing: Add percpu buffers for trace_printk()"
      Cc: stable@vger.kernel.org # v3.5+
      Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
      3debb0a9
  2. 18 Mar, 2016 8 commits
  3. 08 Mar, 2016 12 commits
  4. 06 Mar, 2016 10 commits
  5. 05 Mar, 2016 9 commits