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Subject[PATCH v2 1/9] kgdb: Disable WARN_CONSOLE_UNLOCKED for all kgdb
Date
In commit 81eaadcae81b ("kgdboc: disable the console lock when in
kgdb") we avoided the WARN_CONSOLE_UNLOCKED() yell when we were in
kgdboc. That still works fine, but it turns out that we get a similar
yell when using other I/O drivers. One example is the "I/O driver"
for the kgdb test suite (kgdbts). When I enabled that I again got the
same yells.

Even though "kgdbts" doesn't actually interact with the user over the
console, using it still causes kgdb to print to the consoles. That
trips the same warning:
con_is_visible+0x60/0x68
con_scroll+0x110/0x1b8
lf+0x4c/0xc8
vt_console_print+0x1b8/0x348
vkdb_printf+0x320/0x89c
kdb_printf+0x68/0x90
kdb_main_loop+0x190/0x860
kdb_stub+0x2cc/0x3ec
kgdb_cpu_enter+0x268/0x744
kgdb_handle_exception+0x1a4/0x200
kgdb_compiled_brk_fn+0x34/0x44
brk_handler+0x7c/0xb8
do_debug_exception+0x1b4/0x228

Let's increment/decrement the "ignore_console_lock_warning" variable
all the time when we enter the debugger.

This will allow us to later revert commit 81eaadcae81b ("kgdboc:
disable the console lock when in kgdb").

Signed-off-by: Douglas Anderson <dianders@chromium.org>
---

Changes in v2:
- ("kgdb: Disable WARN_CONSOLE_UNLOCKED for all kgdb") new for v2.

kernel/debug/debug_core.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c
index 2b7c9b67931d..950dc667c823 100644
--- a/kernel/debug/debug_core.c
+++ b/kernel/debug/debug_core.c
@@ -668,6 +668,8 @@ static int kgdb_cpu_enter(struct kgdb_state *ks, struct pt_regs *regs,
if (kgdb_skipexception(ks->ex_vector, ks->linux_regs))
goto kgdb_restore;

+ atomic_inc(&ignore_console_lock_warning);
+
/* Call the I/O driver's pre_exception routine */
if (dbg_io_ops->pre_exception)
dbg_io_ops->pre_exception();
@@ -740,6 +742,8 @@ static int kgdb_cpu_enter(struct kgdb_state *ks, struct pt_regs *regs,
if (dbg_io_ops->post_exception)
dbg_io_ops->post_exception();

+ atomic_dec(&ignore_console_lock_warning);
+
if (!kgdb_single_step) {
raw_spin_unlock(&dbg_slave_lock);
/* Wait till all the CPUs have quit from the debugger. */
--
2.26.1.301.g55bc3eb7cb9-goog
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