)]}'
{
  "commit": "81de916f19cf5f1437c0b9ed817364f0f7c81961",
  "tree": "5c1cda4a096ae3b821a5917de5984b1a16079707",
  "parents": [
    "cb0a02ecf95e5f47d92e7d4c513cc1f7aeb40cda"
  ],
  "author": {
    "name": "Linus Torvalds",
    "email": "torvalds@linux-foundation.org",
    "time": "Wed Jun 08 07:46:30 2011 -0700"
  },
  "committer": {
    "name": "Linus Torvalds",
    "email": "torvalds@linux-foundation.org",
    "time": "Wed Jun 08 07:46:30 2011 -0700"
  },
  "message": "tty_buffer: get rid of \u0027seen_tail\u0027 logic in flush_to_ldisc\n\nThe flush_to_ldisc() work entry has special logic to notice when it has\nseen the original tail of the data queue, and it avoids continuing the\nflush if it sees that _original_ tail rather than the current tail.\n\nThis logic can trigger in case somebody is constantly adding new data to\nthe tty while the flushing is active - and the intent is to avoid\nexcessive CPU usage while flushing the tty, especially as we used to do\nthis from a softirq context which made it non-preemptible.\n\nHowever, since we no longer re-arm the work-queue from within itself\n(because that causes other trouble: see commit a5660b41af6a \"tty: fix\nendless work loop when the buffer fills up\"), this just leads to\npossible hung tty\u0027s (most easily seen in SMP and with a test-program\nthat floods a pty with data - nobody seems to have reported this for any\nreal-life situation yet).\n\nAnd since the workqueue isn\u0027t done from timers and softirq\u0027s any more,\nit\u0027s doubtful whether the CPU useage issue is really relevant any more.\nSo just remove the logic entirely, and see if anybody ever notices.\n\nAlternatively, we might want to re-introduce the \"re-arm the work\" for\njust this case, but then we\u0027d have to re-introduce the delayed work\nmodel or some explicit timer, which really doesn\u0027t seem worth it for\nthis.\n\nReported-and-tested-by: Guillaume Chazarain \u003cguichaz@gmail.com\u003e\nCc: Alan Cox \u003calan@lxorguk.ukuu.org.uk\u003e\nCc: Felipe Balbi \u003cbalbi@ti.com\u003e\nCc: Greg Kroah-Hartman \u003cgregkh@suse.de\u003e\nSigned-off-by: Linus Torvalds \u003ctorvalds@linux-foundation.org\u003e\n",
  "tree_diff": [
    {
      "type": "modify",
      "old_id": "f1a7918d71aac192107af9b45f5e2dde1508383a",
      "old_mode": 33188,
      "old_path": "drivers/tty/tty_buffer.c",
      "new_id": "6c9b7cd6778a9613542d739358f309a38fa56070",
      "new_mode": 33188,
      "new_path": "drivers/tty/tty_buffer.c"
    }
  ]
}