Messages in this thread Patch in this message | | | Subject | Re: [PATCH] tty race on con_close and con_flush_chars | From | Robert Love <> | Date | 29 Oct 2001 22:13:55 -0500 |
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Someone pointed out (via private email) that a race can still exist between checking that vt is non-zero and acquiring the semaphore, especially since we can sleep doing that.
I agree; the following patch should alleviate that race.
diff -u linux-2.4.13-ac5/drivers/char/console.c linux/drivers/char/console.c --- linux-2.4.13-ac5/drivers/char/console.c Mon Oct 29 17:27:19 2001 +++ linux/drivers/char/console.c Mon Oct 29 22:11:27 2001 @@ -2387,8 +2387,14 @@ return; pm_access(pm_con); + + /* + * If we raced with con_close(), `vt' may be null. + * Hence this bandaid. - akpm + */ acquire_console_sem(); - set_cursor(vt->vc_num); + if (vt) + set_cursor(vt->vc_num); release_console_sem(); } Robert Love
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