On 27/04/2022 23:49, Guilherme G. Piccoli wrote:
The goal of this new panic notifier is to allow its users to
register callbacks to run earlier in the panic path than they
currently do. This aims at informational mechanisms, like dumping
kernel offsets and showing device error data (in case it's simple
registers reading, for example) as well as mechanisms to disable
log flooding (like hung_task detector / RCU warnings) and the
tracing dump_on_oops (when enabled).
Any (non-invasive) information that should be provided before
kmsg_dump() as well as log flooding preventing code should fit
here, as long it offers relatively low risk for kdump.
For now, the patch is almost a no-op, although it changes a bit
the ordering in which some panic notifiers are executed - specially
affected by this are the notifiers responsible for disabling the
hung_task detector / RCU warnings, which now run first. In a
subsequent patch, the panic path will be refactored, then the
panic informational notifiers will effectively run earlier,
before ksmg_dump() (and usually before kdump as well).
We also defer documenting it all properly in the subsequent
refactor patch. Finally, while at it, we removed some useless
header inclusions too.
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Florian Fainelli <f.fainelli@xxxxxxxxx>
Cc: Frederic Weisbecker <frederic@xxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Hari Bathini <hbathini@xxxxxxxxxxxxx>
Cc: Joel Fernandes <joel@xxxxxxxxxxxxxxxxx>
Cc: Jonathan Hunter <jonathanh@xxxxxxxxxx>
Cc: Josh Triplett <josh@xxxxxxxxxxxxxxxx>
Cc: Lai Jiangshan <jiangshanlai@xxxxxxxxx>
Cc: Leo Yan <leo.yan@xxxxxxxxxx>
Cc: Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx>
Cc: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: Mike Leach <mike.leach@xxxxxxxxxx>
Cc: Mikko Perttunen <mperttunen@xxxxxxxxxx>
Cc: Neeraj Upadhyay <quic_neeraju@xxxxxxxxxxx>
Cc: Nicholas Piggin <npiggin@xxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
Cc: Thierry Reding <thierry.reding@xxxxxxxxx>
Cc: Thomas Bogendoerfer <tsbogend@xxxxxxxxxxxxxxxx>
Signed-off-by: Guilherme G. Piccoli <gpiccoli@xxxxxxxxxx>
---
arch/arm64/kernel/setup.c | 2 +-
arch/mips/kernel/relocate.c | 2 +-
arch/powerpc/kernel/setup-common.c | 2 +-
arch/x86/kernel/setup.c | 2 +-
drivers/bus/brcmstb_gisb.c | 2 +-
drivers/hwtracing/coresight/coresight-cpu-debug.c | 4 ++--
drivers/soc/tegra/ari-tegra186.c | 3 ++-
include/linux/panic_notifier.h | 1 +
kernel/hung_task.c | 3 ++-
kernel/panic.c | 4 ++++
kernel/rcu/tree.c | 1 -
kernel/rcu/tree_stall.h | 3 ++-
kernel/trace/trace.c | 2 +-
13 files changed, 19 insertions(+), 12 deletions(-)
...
diff --git a/drivers/hwtracing/coresight/coresight-cpu-debug.c b/drivers/hwtracing/coresight/coresight-cpu-debug.c
index 1874df7c6a73..7b1012454525 100644
--- a/drivers/hwtracing/coresight/coresight-cpu-debug.c
+++ b/drivers/hwtracing/coresight/coresight-cpu-debug.c
@@ -535,7 +535,7 @@ static int debug_func_init(void)
&debug_func_knob_fops);
/* Register function to be called for panic */
- ret = atomic_notifier_chain_register(&panic_notifier_list,
+ ret = atomic_notifier_chain_register(&panic_info_list,
&debug_notifier);
if (ret) {
pr_err("%s: unable to register notifier: %d\n",
@@ -552,7 +552,7 @@ static int debug_func_init(void)
static void debug_func_exit(void)
{
- atomic_notifier_chain_unregister(&panic_notifier_list,
+ atomic_notifier_chain_unregister(&panic_info_list,
&debug_notifier);
debugfs_remove_recursive(debug_debugfs_dir);
}
Acked-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
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