forked from Minki/linux
79901317ce
A buffer flush is both undesirable and unnecessary when the ldisc is closing. A buffer flush performs the following: 1. resets ldisc data fields to their initial state 2. resets tty->receive_room to indicate more data can be sent 3. schedules buffer work to receive more data 4. signals a buffer flush has happened to linked pty in packet mode Since the ldisc has been halted and the tty may soon be destructed, buffer work must not be scheduled as that work might access an invalid tty and ldisc state. Also, the ldisc read buffer is about to be freed, so that's pointless. Resetting the ldisc data fields is pointless as well since that structure is about to be freed. Resetting tty->receive_room is unnecessary, as it will be properly reset if a new ldisc is reopened. Besides, resetting the original receive_room value would be wrong since the read buffer will be gone. Since the packet mode flush is observable from userspace, this behavior has been preserved. The test jig originally authored by Ilya Zykov <ilya@ilyx.ru> and signed off by him is included below. The test jig prompts the following warnings which this patch fixes. [ 38.051111] ------------[ cut here ]------------ [ 38.052113] WARNING: at drivers/tty/n_tty.c:160 n_tty_set_room.part.6+0x8b/0xa0() [ 38.053916] Hardware name: Bochs [ 38.054819] Modules linked in: netconsole configfs bnep rfcomm bluetooth parport_pc ppdev snd_hda_intel snd_hda_codec snd_hwdep snd_pcm snd_seq_midi snd_rawmidi snd_seq_midi_event snd_seq psmouse snd_timer serio_raw mac_hid snd_seq_device snd microcode lp parport virtio_balloon soundcore i2c_piix4 snd_page_alloc floppy 8139too 8139cp [ 38.059704] Pid: 1564, comm: pty_kill Tainted: G W 3.7.0-next-20121130+ttydebug-xeon #20121130+ttydebug [ 38.061578] Call Trace: [ 38.062491] [<ffffffff81058b4f>] warn_slowpath_common+0x7f/0xc0 [ 38.063448] [<ffffffff81058baa>] warn_slowpath_null+0x1a/0x20 [ 38.064439] [<ffffffff8142dc2b>] n_tty_set_room.part.6+0x8b/0xa0 [ 38.065381] [<ffffffff8142dc82>] n_tty_set_room+0x42/0x80 [ 38.066323] [<ffffffff8142e6f2>] reset_buffer_flags+0x102/0x160 [ 38.077508] [<ffffffff8142e76d>] n_tty_flush_buffer+0x1d/0x90 [ 38.078782] [<ffffffff81046569>] ? default_spin_lock_flags+0x9/0x10 [ 38.079734] [<ffffffff8142e804>] n_tty_close+0x24/0x60 [ 38.080730] [<ffffffff81431b61>] tty_ldisc_close.isra.2+0x41/0x60 [ 38.081680] [<ffffffff81431bbb>] tty_ldisc_kill+0x3b/0x80 [ 38.082618] [<ffffffff81432a07>] tty_ldisc_release+0x77/0xe0 [ 38.083549] [<ffffffff8142b781>] tty_release+0x451/0x4d0 [ 38.084525] [<ffffffff811950be>] __fput+0xae/0x230 [ 38.085472] [<ffffffff8119524e>] ____fput+0xe/0x10 [ 38.086401] [<ffffffff8107aa88>] task_work_run+0xc8/0xf0 [ 38.087334] [<ffffffff8105ea56>] do_exit+0x196/0x4b0 [ 38.088304] [<ffffffff8106c77b>] ? __dequeue_signal+0x6b/0xb0 [ 38.089240] [<ffffffff8105ef34>] do_group_exit+0x44/0xa0 [ 38.090182] [<ffffffff8106f43d>] get_signal_to_deliver+0x20d/0x4e0 [ 38.091125] [<ffffffff81016979>] do_signal+0x29/0x130 [ 38.092096] [<ffffffff81431a9e>] ? tty_ldisc_deref+0xe/0x10 [ 38.093030] [<ffffffff8142a317>] ? tty_write+0xb7/0xf0 [ 38.093976] [<ffffffff81193f53>] ? vfs_write+0xb3/0x180 [ 38.094904] [<ffffffff81016b20>] do_notify_resume+0x80/0xc0 [ 38.095830] [<ffffffff81700492>] int_signal+0x12/0x17 [ 38.096788] ---[ end trace 5f6f7a9651cd999b ]--- [ 2730.570602] ------------[ cut here ]------------ [ 2730.572130] WARNING: at drivers/tty/n_tty.c:160 n_tty_set_room+0x107/0x140() [ 2730.574904] scheduling buffer work for halted ldisc [ 2730.578303] Pid: 9691, comm: trinity-child15 Tainted: G W 3.7.0-rc8-next-20121205-sasha-00023-g59f0d85 #207 [ 2730.588694] Call Trace: [ 2730.590486] [<ffffffff81c41d77>] ? n_tty_set_room+0x107/0x140 [ 2730.592559] [<ffffffff8110c827>] warn_slowpath_common+0x87/0xb0 [ 2730.595317] [<ffffffff8110c8b1>] warn_slowpath_fmt+0x41/0x50 [ 2730.599186] [<ffffffff81c41d77>] n_tty_set_room+0x107/0x140 [ 2730.603141] [<ffffffff81c42fe7>] reset_buffer_flags+0x137/0x150 [ 2730.607166] [<ffffffff81c43018>] n_tty_flush_buffer+0x18/0x90 [ 2730.610123] [<ffffffff81c430af>] n_tty_close+0x1f/0x60 [ 2730.612068] [<ffffffff81c461f2>] tty_ldisc_close.isra.4+0x52/0x60 [ 2730.614078] [<ffffffff81c462ab>] tty_ldisc_reinit+0x3b/0x70 [ 2730.615891] [<ffffffff81c46db2>] tty_ldisc_hangup+0x102/0x1e0 [ 2730.617780] [<ffffffff81c3e537>] __tty_hangup+0x137/0x440 [ 2730.619547] [<ffffffff81c3e869>] tty_vhangup+0x9/0x10 [ 2730.621266] [<ffffffff81c48f1c>] pty_close+0x14c/0x160 [ 2730.622952] [<ffffffff81c3fd45>] tty_release+0xd5/0x490 [ 2730.624674] [<ffffffff8127fbe2>] __fput+0x122/0x250 [ 2730.626195] [<ffffffff8127fd19>] ____fput+0x9/0x10 [ 2730.627758] [<ffffffff81134602>] task_work_run+0xb2/0xf0 [ 2730.629491] [<ffffffff811139ad>] do_exit+0x36d/0x580 [ 2730.631159] [<ffffffff81113c8a>] do_group_exit+0x8a/0xc0 [ 2730.632819] [<ffffffff81127351>] get_signal_to_deliver+0x501/0x5b0 [ 2730.634758] [<ffffffff8106de34>] do_signal+0x24/0x100 [ 2730.636412] [<ffffffff81204865>] ? user_exit+0xa5/0xd0 [ 2730.638078] [<ffffffff81183cd8>] ? trace_hardirqs_on_caller+0x118/0x140 [ 2730.640279] [<ffffffff81183d0d>] ? trace_hardirqs_on+0xd/0x10 [ 2730.642164] [<ffffffff8106df78>] do_notify_resume+0x48/0xa0 [ 2730.643966] [<ffffffff83cdff6a>] int_signal+0x12/0x17 [ 2730.645672] ---[ end trace a40d53149c07fce0 ]--- /* * pty_thrash.c * * Based on original test jig by Ilya Zykov <ilya@ilyx.ru> * * Signed-off-by: Peter Hurley <peter@hurleysoftware.com> * Signed-off-by: Ilya Zykov <ilya@ilyx.ru> */ static int fd; static void error_exit(char *f, ...) { va_list va; va_start(va, f); vprintf(f, va); printf(": %s\n", strerror(errno)); va_end(va); if (fd >= 0) close(fd); exit(EXIT_FAILURE); } int main(int argc, char *argv[]) { int parent; char pts_name[24]; int ptn, unlock; while (1) { fd = open("/dev/ptmx", O_RDWR); if (fd < 0) error_exit("opening pty master"); unlock = 0; if (ioctl(fd, TIOCSPTLCK, &unlock) < 0) error_exit("unlocking pty pair"); if (ioctl(fd, TIOCGPTN, &ptn) < 0) error_exit("getting pty #"); snprintf(pts_name, sizeof(pts_name), "/dev/pts/%d", ptn); child_id = fork(); if (child_id == -1) error_exit("forking child"); if (parent) { int err, id, status; char buf[128]; int n; n = read(fd, buf, sizeof(buf)); if (n < 0) error_exit("master reading"); printf("%.*s\n", n-1, buf); close(fd); err = kill(child_id, SIGKILL); if (err < 0) error_exit("killing child"); id = waitpid(child_id, &status, 0); if (id < 0 || id != child_id) error_exit("waiting for child"); } else { /* Child */ close(fd); printf("Test cycle on slave pty %s\n", pts_name); fd = open(pts_name, O_RDWR); if (fd < 0) error_exit("opening pty slave"); while (1) { char pattern[] = "test\n"; if (write(fd, pattern, strlen(pattern)) < 0) error_exit("slave writing"); } } } /* never gets here */ return 0; } Reported-by: Sasha Levin <levinsasha928@gmail.com> Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
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| .. | ||
| hvc | ||
| ipwireless | ||
| serial | ||
| vt | ||
| amiserial.c | ||
| bfin_jtag_comm.c | ||
| cyclades.c | ||
| ehv_bytechan.c | ||
| goldfish.c | ||
| isicom.c | ||
| Kconfig | ||
| Makefile | ||
| metag_da.c | ||
| moxa.c | ||
| moxa.h | ||
| mxser.c | ||
| mxser.h | ||
| n_gsm.c | ||
| n_hdlc.c | ||
| n_r3964.c | ||
| n_tracerouter.c | ||
| n_tracesink.c | ||
| n_tracesink.h | ||
| n_tty.c | ||
| nozomi.c | ||
| pty.c | ||
| rocket_int.h | ||
| rocket.c | ||
| rocket.h | ||
| synclink_gt.c | ||
| synclink.c | ||
| synclinkmp.c | ||
| sysrq.c | ||
| tty_audit.c | ||
| tty_buffer.c | ||
| tty_io.c | ||
| tty_ioctl.c | ||
| tty_ldisc.c | ||
| tty_mutex.c | ||
| tty_port.c | ||