Eric Lee / smarc-fsl-linux-kernel

Download as
Browse Code ยป

Commit 487ad7efbf6b0ec338cdfc2a7b0fbeb53f17a94c

Authored by Ingo Molnar
Committed by Linus Torvalds
1 parent 8568dae21e
Exists in master and in 39 other branches 8mp-imx_5.4.70_2.3.0, 8qm-imx_5.4.70_2.3.0, emb_imx_lf-5.15.y, emb_lf-6.1.y, imx_3.0.35_4.1.0, imx_3.10.17_1.0.1_ga, imx_3.10.53_1.1.0_ga, imx_3.14.28_1.0.0_ga, imx_4.1.15_1.0.0_ga, pitx_8mp_lf-5.10.y, rt-smarc-imx_4.1.15_1.0.0_ga, rt_linux_5.15.71, smarc-8m-android-11.0.0_2.0.0, smarc-imx6_4.14.98_2.0.0_ga, smarc-imx6_4.9.88_2.0.0_ga, smarc-imx7_4.14.98_2.0.0_ga, smarc-imx7_4.9.11_1.0.0_ga, smarc-imx7_4.9.88_2.0.0_ga, smarc-imx_3.10.53_1.1.0_ga, smarc-imx_3.14.28_1.0.0_ga, smarc-imx_4.1.15_1.0.0_ga, smarc-imx_4.9.11_1.0.0_ga, smarc-imx_4.9.51_imx8m_ga, smarc-imx_4.9.88_2.0.0_ga, smarc-m6.0.1_2.1.0-ga, smarc-n7.1.2_2.0.0-ga, smarc-rel_imx_4.1.15_1.2.0_ga, smarc_8m_00d0_imx_4.14.98_2.0.0_ga, smarc_8m_imx_4.14.78_1.0.0_ga, smarc_8m_imx_4.14.98_2.0.0_ga, smarc_8m_imx_4.19.35_1.1.0, smarc_8mm_imx_4.14.78_1.0.0_ga, smarc_8mm_imx_4.14.98_2.0.0_ga, smarc_8mm_imx_4.19.35_1.1.0, smarc_8mm_imx_5.4.24_2.1.0, smarc_8mp_lf-5.10.y, smarc_8mq_imx_5.4.24_2.1.0, smarc_8mq_lf-5.10.y, smarc_imx_lf-5.15.y

tty: fix BKL related leak and crash 

Enabling the BKL to be lockdep tracked uncovered the following
upstream kernel bug in the tty code, which caused a BKL
reference leak:

  ================================================
  [ BUG: lock held when returning to user space! ]
  ------------------------------------------------
  dmesg/3121 is leaving the kernel with locks still held!
  1 lock held by dmesg/3121:
   #0:  (kernel_mutex){--..}, at: [<c02f34d9>] opost+0x24/0x194

this might explain some of the atomicity warnings and crashes
that -tip tree testing has been experiencing since the BKL
was converted back to a spinlock.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Showing 1 changed file with 10 additions and 3 deletions Side-by-side Diff

drivers/char/n_tty.c
Diff comments   View file @ 487ad7e
... ... @@ -282,16 +282,20 @@
282 282 if (O_ONLRET(tty))
283 283 tty->column = 0;
284 284 if (O_ONLCR(tty)) {
285   - if (space < 2)
  285 + if (space < 2) {
  286 + unlock_kernel();
286 287 return -1;
  288 + }
287 289 tty_put_char(tty, '\r');
288 290 tty->column = 0;
289 291 }
290 292 tty->canon_column = tty->column;
291 293 break;
292 294 case '\r':
293   - if (O_ONOCR(tty) && tty->column == 0)
  295 + if (O_ONOCR(tty) && tty->column == 0) {
  296 + unlock_kernel();
294 297 return 0;
  298 + }
295 299 if (O_OCRNL(tty)) {
296 300 c = '\n';
297 301 if (O_ONLRET(tty))
298 302  
299 303  
... ... @@ -303,10 +307,13 @@
303 307 case '\t':
304 308 spaces = 8 - (tty->column & 7);
305 309 if (O_TABDLY(tty) == XTABS) {
306   - if (space < spaces)
  310 + if (space < spaces) {
  311 + unlock_kernel();
307 312 return -1;
  313 + }
308 314 tty->column += spaces;
309 315 tty->ops->write(tty, " ", spaces);
  316 + unlock_kernel();
310 317 return 0;
311 318 }
312 319 tty->column += spaces;