summaryrefslogtreecommitdiff
path: root/kernel/debug
diff options
context:
space:
mode:
authorDouglas Anderson <dianders@chromium.org>2020-05-26 14:20:06 -0700
committerDaniel Thompson <daniel.thompson@linaro.org>2020-06-02 15:15:45 +0100
commitb1350132fef7e1f0ddfd5a985d516a6ed7a329fc (patch)
treeab72a18e652011163b2c8800f312d9e9375396a2 /kernel/debug
parent1feb48baf2fb2aff02aa734c04a3ba5c3297d2de (diff)
kgdb: Don't call the deinit under spinlock
When I combined kgdboc_earlycon with an inflight patch titled ("soc: qcom-geni-se: Add interconnect support to fix earlycon crash") [1] things went boom. Specifically I got a crash during the transition between kgdboc_earlycon and the main kgdboc that looked like this: Call trace: __schedule_bug+0x68/0x6c __schedule+0x75c/0x924 schedule+0x8c/0xbc schedule_timeout+0x9c/0xfc do_wait_for_common+0xd0/0x160 wait_for_completion_timeout+0x54/0x74 rpmh_write_batch+0x1fc/0x23c qcom_icc_bcm_voter_commit+0x1b4/0x388 qcom_icc_set+0x2c/0x3c apply_constraints+0x5c/0x98 icc_set_bw+0x204/0x3bc icc_put+0x30/0xf8 geni_remove_earlycon_icc_vote+0x6c/0x9c qcom_geni_serial_earlycon_exit+0x10/0x1c kgdboc_earlycon_deinit+0x38/0x58 kgdb_register_io_module+0x11c/0x194 configure_kgdboc+0x108/0x174 kgdboc_probe+0x38/0x60 platform_drv_probe+0x90/0xb0 really_probe+0x130/0x2fc ... The problem was that we were holding the "kgdb_registration_lock" while calling into code that didn't expect to be called in spinlock context. Let's slightly defer when we call the deinit code so that it's not done under spinlock. NOTE: this does mean that the "deinit" call of the old kgdb IO module is now made _after_ the init of the new IO module, but presumably that's OK. [1] https://lkml.kernel.org/r/1588919619-21355-3-git-send-email-akashast@codeaurora.org Fixes: 220995622da5 ("kgdboc: Add kgdboc_earlycon to support early kgdb using boot consoles") Signed-off-by: Douglas Anderson <dianders@chromium.org> Link: https://lore.kernel.org/r/20200526142001.1.I523dc33f96589cb9956f5679976d402c8cda36fa@changeid [daniel.thompson@linaro.org: Resolved merge issues by hand] Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Diffstat (limited to 'kernel/debug')
-rw-r--r--kernel/debug/debug_core.c5
1 files changed, 3 insertions, 2 deletions
diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c
index 4d59aa907fdc..ef94e906f05a 100644
--- a/kernel/debug/debug_core.c
+++ b/kernel/debug/debug_core.c
@@ -1089,7 +1089,6 @@ int kgdb_register_io_module(struct kgdb_io *new_dbg_io_ops)
}
pr_info("Replacing I/O driver %s with %s\n",
old_dbg_io_ops->name, new_dbg_io_ops->name);
- old_dbg_io_ops->deinit();
}
if (new_dbg_io_ops->init) {
@@ -1104,8 +1103,10 @@ int kgdb_register_io_module(struct kgdb_io *new_dbg_io_ops)
spin_unlock(&kgdb_registration_lock);
- if (old_dbg_io_ops)
+ if (old_dbg_io_ops) {
+ old_dbg_io_ops->deinit();
return 0;
+ }
pr_info("Registered I/O driver %s\n", new_dbg_io_ops->name);