printk, tracing: Avoiding unneeded blank lines
Printk messages often finish with '\n' to cause a new line. But as each tracepoint is already printed in a new line, printk messages that finish with '\n' ends up adding a blank line to the trace output. For example: kworker/0:1-86 [000] d... 46.006949: console: [ 46.006946] usb 1-3: USB disconnect, device number 3 kworker/2:2-374 [002] d... 48.699342: console: [ 48.699339] usb 1-3: new high-speed USB device number 4 using ehci-pci kworker/2:2-374 [002] d... 49.041450: console: [ 49.041448] usb 1-3: New USB device found, idVendor=5986, idProduct=0 To avoid unneeded blank lines, this patch checks if the printk message finishes with '\n', if so, it cut is off the '\n' to avoid blank lines. In a patched kernel, the same messages are printed without extra blank lines. For example: kworker/0:4-185 [000] d... 23.641738: console: [ 23.641736] usb 1-3: USB disconnect, device number 3 kworker/0:4-185 [000] d... 24.918703: console: [ 24.918700] usb 1-3: new high-speed USB device number 4 using ehci-pci kworker/0:4-185 [000] d... 25.228308: console: [ 25.228306] usb 1-3: New USB device found, idVendor=5986, idProduct=02d5 Link: http://lkml.kernel.org/r/c350fb2521baaf681a1b4d67981ca0e900108e8e.1467407618.git.bristot@redhat.com Cc: Trond Myklebust <trond.myklebust@primarydata.com> Cc: Anna Schumaker <anna.schumaker@netapp.com> Cc: Ingo Molnar <mingo@redhat.com> Reviewed-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Daniel Bristot de Oliveira <bristot@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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@ -16,6 +16,14 @@ TRACE_EVENT(console,
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TP_fast_assign(
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/*
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* Each trace entry is printed in a new line.
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* If the msg finishes with '\n', cut it off
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* to avoid blank lines in the trace.
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*/
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if ((len > 0) && (text[len-1] == '\n'))
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len -= 1;
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memcpy(__get_str(msg), text, len);
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__get_str(msg)[len] = 0;
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),
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