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| author | John Ogness <john.ogness@linutronix.de> | 2022-11-16 19:21:26 +0300 |
|---|---|---|
| committer | Petr Mladek <pmladek@suse.com> | 2022-12-02 13:25:00 +0300 |
| commit | b8ef04be6e1935748ef98af98d81b0744cf225d0 (patch) | |
| tree | c0a2bcc058f2ba2750e763643b1fdbfeb8b68eb7 /kernel/debug | |
| parent | 12335446e06f1b3c9112576f894df856d3d466fc (diff) | |
| download | linux-b8ef04be6e1935748ef98af98d81b0744cf225d0.tar.xz | |
kdb: use srcu console list iterator
Guarantee safe iteration of the console list by using SRCU.
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: Aaron Tomlin <atomlin@atomlin.com>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20221116162152.193147-15-john.ogness@linutronix.de
Diffstat (limited to 'kernel/debug')
| -rw-r--r-- | kernel/debug/kdb/kdb_io.c | 18 |
1 files changed, 16 insertions, 2 deletions
diff --git a/kernel/debug/kdb/kdb_io.c b/kernel/debug/kdb/kdb_io.c index 67d3c48a1522..5c7e9ba7cd6b 100644 --- a/kernel/debug/kdb/kdb_io.c +++ b/kernel/debug/kdb/kdb_io.c @@ -545,6 +545,7 @@ static void kdb_msg_write(const char *msg, int msg_len) { struct console *c; const char *cp; + int cookie; int len; if (msg_len == 0) @@ -558,8 +559,20 @@ static void kdb_msg_write(const char *msg, int msg_len) cp++; } - for_each_console(c) { - if (!(c->flags & CON_ENABLED)) + /* + * The console_srcu_read_lock() only provides safe console list + * traversal. The use of the ->write() callback relies on all other + * CPUs being stopped at the moment and console drivers being able to + * handle reentrance when @oops_in_progress is set. + * + * There is no guarantee that every console driver can handle + * reentrance in this way; the developer deploying the debugger + * is responsible for ensuring that the console drivers they + * have selected handle reentrance appropriately. + */ + cookie = console_srcu_read_lock(); + for_each_console_srcu(c) { + if (!(console_srcu_read_flags(c) & CON_ENABLED)) continue; if (c == dbg_io_ops->cons) continue; @@ -577,6 +590,7 @@ static void kdb_msg_write(const char *msg, int msg_len) --oops_in_progress; touch_nmi_watchdog(); } + console_srcu_read_unlock(cookie); } int vkdb_printf(enum kdb_msgsrc src, const char *fmt, va_list ap) |