| Message ID | 20220427224924.592546-23-gpiccoli@igalia.com (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
| Series | The panic notifiers refactor | expand |
On 27/04/2022 19:49, Guilherme G. Piccoli wrote: > Currently we have 3 notifier lists in the panic path, which will > be wired in a way to allow the notifier callbacks to run in > different moments at panic time, in a subsequent patch. > > But there is also an odd set of architecture calls hardcoded in > the end of panic path, after the restart machinery. They're > responsible for late time tunings / events, like enabling a stop > button (Sparc) or effectively stopping the machine (s390). > > This patch introduces yet another notifier list to offer the > architectures a way to add callbacks in such late moment on > panic path without the need of ifdefs / hardcoded approaches. > > Cc: Alexander Gordeev <agordeev@linux.ibm.com> > Cc: Christian Borntraeger <borntraeger@linux.ibm.com> > Cc: "David S. Miller" <davem@davemloft.net> > Cc: Heiko Carstens <hca@linux.ibm.com> > Cc: Sven Schnelle <svens@linux.ibm.com> > Cc: Vasily Gorbik <gor@linux.ibm.com> > Signed-off-by: Guilherme G. Piccoli <gpiccoli@igalia.com> Hey S390/SPARC folks, sorry for the ping! Any reviews on this V1 would be greatly appreciated, I'm working on V2 and seeking feedback in the non-reviewed patches. Thanks in advance, Guilherme
On Mon, May 09, 2022 at 11:16:10AM -0300, Guilherme G. Piccoli wrote: > On 27/04/2022 19:49, Guilherme G. Piccoli wrote: > > Currently we have 3 notifier lists in the panic path, which will > > be wired in a way to allow the notifier callbacks to run in > > different moments at panic time, in a subsequent patch. > > > > But there is also an odd set of architecture calls hardcoded in > > the end of panic path, after the restart machinery. They're > > responsible for late time tunings / events, like enabling a stop > > button (Sparc) or effectively stopping the machine (s390). > > > > This patch introduces yet another notifier list to offer the > > architectures a way to add callbacks in such late moment on > > panic path without the need of ifdefs / hardcoded approaches. > > > > Cc: Alexander Gordeev <agordeev@linux.ibm.com> > > Cc: Christian Borntraeger <borntraeger@linux.ibm.com> > > Cc: "David S. Miller" <davem@davemloft.net> > > Cc: Heiko Carstens <hca@linux.ibm.com> > > Cc: Sven Schnelle <svens@linux.ibm.com> > > Cc: Vasily Gorbik <gor@linux.ibm.com> > > Signed-off-by: Guilherme G. Piccoli <gpiccoli@igalia.com> > > Hey S390/SPARC folks, sorry for the ping! > > Any reviews on this V1 would be greatly appreciated, I'm working on V2 > and seeking feedback in the non-reviewed patches. Sorry, missed that this is quite s390 specific. So, yes, this looks good to me and nice to see that one of the remaining CONFIG_S390 in common code will be removed! For the s390 bits: Acked-by: Heiko Carstens <hca@linux.ibm.com>
On 11/05/2022 13:45, Heiko Carstens wrote: > [...] >> >> Hey S390/SPARC folks, sorry for the ping! >> >> Any reviews on this V1 would be greatly appreciated, I'm working on V2 >> and seeking feedback in the non-reviewed patches. > > Sorry, missed that this is quite s390 specific. So, yes, this looks > good to me and nice to see that one of the remaining CONFIG_S390 in > common code will be removed! > > For the s390 bits: > Acked-by: Heiko Carstens <hca@linux.ibm.com> No need for apologies, I really appreciate your review! Will add your Ack for V2 =) Cheers, Guilherme
On Wed 2022-04-27 19:49:16, Guilherme G. Piccoli wrote: > Currently we have 3 notifier lists in the panic path, which will > be wired in a way to allow the notifier callbacks to run in > different moments at panic time, in a subsequent patch. > > But there is also an odd set of architecture calls hardcoded in > the end of panic path, after the restart machinery. They're > responsible for late time tunings / events, like enabling a stop > button (Sparc) or effectively stopping the machine (s390). > > This patch introduces yet another notifier list to offer the > architectures a way to add callbacks in such late moment on > panic path without the need of ifdefs / hardcoded approaches. The patch looks good to me. I would just suggest two changes. 1. I would rename the list to "panic_loop_list" instead of "panic_post_reboot_list". It will be more clear that it includes things that are needed before panic() enters the infinite loop. 2. I would move all the notifiers that enable blinking here. The blinking should be done only during the infinite loop when there is nothing else to do. If we enable earlier then it might disturb/break more important functionality (dumping information, reboot). Best Regards, Petr
On 16/05/2022 11:45, Petr Mladek wrote: > [...] > > The patch looks good to me. I would just suggest two changes. > > 1. I would rename the list to "panic_loop_list" instead of > "panic_post_reboot_list". > > It will be more clear that it includes things that are > needed before panic() enters the infinite loop. > > > 2. I would move all the notifiers that enable blinking here. > > The blinking should be done only during the infinite > loop when there is nothing else to do. If we enable > earlier then it might disturb/break more important > functionality (dumping information, reboot). > Perfect, I agree with you. I'll change both points in V2 =)
diff --git a/arch/s390/kernel/setup.c b/arch/s390/kernel/setup.c index d860ac300919..d816b2045f1e 100644 --- a/arch/s390/kernel/setup.c +++ b/arch/s390/kernel/setup.c @@ -39,7 +39,6 @@ #include <linux/kernel_stat.h> #include <linux/dma-map-ops.h> #include <linux/device.h> -#include <linux/notifier.h> #include <linux/pfn.h> #include <linux/ctype.h> #include <linux/reboot.h> @@ -51,6 +50,7 @@ #include <linux/start_kernel.h> #include <linux/hugetlb.h> #include <linux/kmemleak.h> +#include <linux/panic_notifier.h> #include <asm/boot_data.h> #include <asm/ipl.h> @@ -943,6 +943,20 @@ static void __init log_component_list(void) } } +/* + * The following notifier executes as one of the latest things in the panic + * path, only if the restart routines weren't executed (or didn't succeed). + */ +static int panic_event(struct notifier_block *n, unsigned long ev, void *unused) +{ + disabled_wait(); + return NOTIFY_DONE; +} + +static struct notifier_block post_reboot_panic_block = { + .notifier_call = panic_event, +}; + /* * Setup function called from init/main.c just after the banner * was printed. @@ -1058,4 +1072,7 @@ void __init setup_arch(char **cmdline_p) /* Add system specific data to the random pool */ setup_randomness(); + + atomic_notifier_chain_register(&panic_post_reboot_list, + &post_reboot_panic_block); } diff --git a/arch/sparc/kernel/setup_32.c b/arch/sparc/kernel/setup_32.c index c8e0dd99f370..4e2428972f76 100644 --- a/arch/sparc/kernel/setup_32.c +++ b/arch/sparc/kernel/setup_32.c @@ -34,6 +34,7 @@ #include <linux/kdebug.h> #include <linux/export.h> #include <linux/start_kernel.h> +#include <linux/panic_notifier.h> #include <uapi/linux/mount.h> #include <asm/io.h> @@ -51,6 +52,7 @@ #include "kernel.h" +int stop_a_enabled = 1; struct screen_info screen_info = { 0, 0, /* orig-x, orig-y */ 0, /* unused */ @@ -293,6 +295,24 @@ void __init sparc32_start_kernel(struct linux_romvec *rp) start_kernel(); } +/* + * The following notifier executes as one of the latest things in the panic + * path, only if the restart routines weren't executed (or didn't succeed). + */ +static int panic_event(struct notifier_block *n, unsigned long ev, void *unused) +{ + /* Make sure the user can actually press Stop-A (L1-A) */ + stop_a_enabled = 1; + pr_emerg("Press Stop-A (L1-A) from sun keyboard or send break\n" + "twice on console to return to the boot prom\n"); + + return NOTIFY_DONE; +} + +static struct notifier_block post_reboot_panic_block = { + .notifier_call = panic_event, +}; + void __init setup_arch(char **cmdline_p) { int i; @@ -368,9 +388,10 @@ void __init setup_arch(char **cmdline_p) paging_init(); smp_setup_cpu_possible_map(); -} -extern int stop_a_enabled; + atomic_notifier_chain_register(&panic_post_reboot_list, + &post_reboot_panic_block); +} void sun_do_break(void) { @@ -384,8 +405,6 @@ void sun_do_break(void) } EXPORT_SYMBOL(sun_do_break); -int stop_a_enabled = 1; - static int __init topology_init(void) { int i, ncpus, err; diff --git a/arch/sparc/kernel/setup_64.c b/arch/sparc/kernel/setup_64.c index 48abee4eee29..9066c25ecc07 100644 --- a/arch/sparc/kernel/setup_64.c +++ b/arch/sparc/kernel/setup_64.c @@ -33,6 +33,7 @@ #include <linux/module.h> #include <linux/start_kernel.h> #include <linux/memblock.h> +#include <linux/panic_notifier.h> #include <uapi/linux/mount.h> #include <asm/io.h> @@ -62,6 +63,8 @@ #include "entry.h" #include "kernel.h" +int stop_a_enabled = 1; + /* Used to synchronize accesses to NatSemi SUPER I/O chip configure * operations in asm/ns87303.h */ @@ -632,6 +635,24 @@ void __init alloc_irqstack_bootmem(void) } } +/* + * The following notifier executes as one of the latest things in the panic + * path, only if the restart routines weren't executed (or didn't succeed). + */ +static int panic_event(struct notifier_block *n, unsigned long ev, void *unused) +{ + /* Make sure the user can actually press Stop-A (L1-A) */ + stop_a_enabled = 1; + pr_emerg("Press Stop-A (L1-A) from sun keyboard or send break\n" + "twice on console to return to the boot prom\n"); + + return NOTIFY_DONE; +} + +static struct notifier_block post_reboot_panic_block = { + .notifier_call = panic_event, +}; + void __init setup_arch(char **cmdline_p) { /* Initialize PROM console and command line. */ @@ -691,9 +712,10 @@ void __init setup_arch(char **cmdline_p) * allocate the IRQ stacks. */ alloc_irqstack_bootmem(); -} -extern int stop_a_enabled; + atomic_notifier_chain_register(&panic_post_reboot_list, + &post_reboot_panic_block); +} void sun_do_break(void) { @@ -706,6 +728,3 @@ void sun_do_break(void) prom_cmdline(); } EXPORT_SYMBOL(sun_do_break); - -int stop_a_enabled = 1; -EXPORT_SYMBOL(stop_a_enabled); diff --git a/include/linux/panic_notifier.h b/include/linux/panic_notifier.h index 7912aacbc0e5..bcf6a5ea9d7f 100644 --- a/include/linux/panic_notifier.h +++ b/include/linux/panic_notifier.h @@ -8,6 +8,7 @@ extern struct atomic_notifier_head panic_hypervisor_list; extern struct atomic_notifier_head panic_info_list; extern struct atomic_notifier_head panic_pre_reboot_list; +extern struct atomic_notifier_head panic_post_reboot_list; extern bool crash_kexec_post_notifiers; diff --git a/kernel/panic.c b/kernel/panic.c index a9d43b98b05b..bf792102b43e 100644 --- a/kernel/panic.c +++ b/kernel/panic.c @@ -78,6 +78,9 @@ EXPORT_SYMBOL(panic_info_list); ATOMIC_NOTIFIER_HEAD(panic_pre_reboot_list); EXPORT_SYMBOL(panic_pre_reboot_list); +ATOMIC_NOTIFIER_HEAD(panic_post_reboot_list); +EXPORT_SYMBOL(panic_post_reboot_list); + static long no_blink(int state) { return 0; @@ -359,18 +362,10 @@ void panic(const char *fmt, ...) reboot_mode = panic_reboot_mode; emergency_restart(); } -#ifdef __sparc__ - { - extern int stop_a_enabled; - /* Make sure the user can actually press Stop-A (L1-A) */ - stop_a_enabled = 1; - pr_emerg("Press Stop-A (L1-A) from sun keyboard or send break\n" - "twice on console to return to the boot prom\n"); - } -#endif -#if defined(CONFIG_S390) - disabled_wait(); -#endif + + atomic_notifier_call_chain(&panic_post_reboot_list, + PANIC_NOTIFIER, buf); + pr_emerg("---[ end Kernel panic - not syncing: %s ]---\n", buf); /* Do not scroll important messages printed above */
Currently we have 3 notifier lists in the panic path, which will be wired in a way to allow the notifier callbacks to run in different moments at panic time, in a subsequent patch. But there is also an odd set of architecture calls hardcoded in the end of panic path, after the restart machinery. They're responsible for late time tunings / events, like enabling a stop button (Sparc) or effectively stopping the machine (s390). This patch introduces yet another notifier list to offer the architectures a way to add callbacks in such late moment on panic path without the need of ifdefs / hardcoded approaches. Cc: Alexander Gordeev <agordeev@linux.ibm.com> Cc: Christian Borntraeger <borntraeger@linux.ibm.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: Heiko Carstens <hca@linux.ibm.com> Cc: Sven Schnelle <svens@linux.ibm.com> Cc: Vasily Gorbik <gor@linux.ibm.com> Signed-off-by: Guilherme G. Piccoli <gpiccoli@igalia.com> --- arch/s390/kernel/setup.c | 19 ++++++++++++++++++- arch/sparc/kernel/setup_32.c | 27 +++++++++++++++++++++++---- arch/sparc/kernel/setup_64.c | 29 ++++++++++++++++++++++++----- include/linux/panic_notifier.h | 1 + kernel/panic.c | 19 +++++++------------ 5 files changed, 73 insertions(+), 22 deletions(-)