[PATCH v2] printk: Add a short description string to kmsg_dump()
Jocelyn Falempe
jfalempe at redhat.com
Fri Jul 12 19:59:30 AEST 2024
On 02/07/2024 14:26, Jocelyn Falempe wrote:
> kmsg_dump doesn't forward the panic reason string to the kmsg_dumper
> callback.
> This patch adds a new struct kmsg_dump_detail, that will hold the
> reason and description, and pass it to the dump() callback.
>
> To avoid updating all kmsg_dump() call, it adds a kmsg_dump_desc()
> function and a macro for backward compatibility.
>
> I've written this for drm_panic, but it can be useful for other
> kmsg_dumper.
> It allows to see the panic reason, like "sysrq triggered crash"
> or "VFS: Unable to mount root fs on xxxx" on the drm panic screen.
>
> v2:
> * Use a struct kmsg_dump_detail to hold the reason and description
> pointer, for more flexibility if we want to add other parameters.
> (Kees Cook)
> * Fix powerpc/nvram_64 build, as I didn't update the forward
> declaration of oops_to_nvram()
>
> Signed-off-by: Jocelyn Falempe <jfalempe at redhat.com>
> ---
> arch/powerpc/kernel/nvram_64.c | 8 ++++----
> arch/powerpc/platforms/powernv/opal-kmsg.c | 4 ++--
> arch/um/kernel/kmsg_dump.c | 2 +-
> drivers/gpu/drm/drm_panic.c | 4 ++--
> drivers/hv/hv_common.c | 4 ++--
> drivers/mtd/mtdoops.c | 2 +-
> fs/pstore/platform.c | 10 +++++-----
> include/linux/kmsg_dump.h | 22 +++++++++++++++++++---
> kernel/panic.c | 2 +-
> kernel/printk/printk.c | 11 ++++++++---
> 10 files changed, 45 insertions(+), 24 deletions(-)
>
> diff --git a/arch/powerpc/kernel/nvram_64.c b/arch/powerpc/kernel/nvram_64.c
> index e385d3164648..f9c6568a9137 100644
> --- a/arch/powerpc/kernel/nvram_64.c
> +++ b/arch/powerpc/kernel/nvram_64.c
> @@ -73,7 +73,7 @@ static const char *nvram_os_partitions[] = {
> };
>
> static void oops_to_nvram(struct kmsg_dumper *dumper,
> - enum kmsg_dump_reason reason);
> + struct kmsg_dump_detail *detail);
>
> static struct kmsg_dumper nvram_kmsg_dumper = {
> .dump = oops_to_nvram
> @@ -643,7 +643,7 @@ void __init nvram_init_oops_partition(int rtas_partition_exists)
> * partition. If that's too much, go back and capture uncompressed text.
> */
> static void oops_to_nvram(struct kmsg_dumper *dumper,
> - enum kmsg_dump_reason reason)
> + struct kmsg_dump_detail *detail)
> {
> struct oops_log_info *oops_hdr = (struct oops_log_info *)oops_buf;
> static unsigned int oops_count = 0;
> @@ -655,7 +655,7 @@ static void oops_to_nvram(struct kmsg_dumper *dumper,
> unsigned int err_type = ERR_TYPE_KERNEL_PANIC_GZ;
> int rc = -1;
>
> - switch (reason) {
> + switch (detail->reason) {
> case KMSG_DUMP_SHUTDOWN:
> /* These are almost always orderly shutdowns. */
> return;
> @@ -671,7 +671,7 @@ static void oops_to_nvram(struct kmsg_dumper *dumper,
> break;
> default:
> pr_err("%s: ignoring unrecognized KMSG_DUMP_* reason %d\n",
> - __func__, (int) reason);
> + __func__, (int) detail->reason);
> return;
> }
>
> diff --git a/arch/powerpc/platforms/powernv/opal-kmsg.c b/arch/powerpc/platforms/powernv/opal-kmsg.c
> index 6c3bc4b4da98..bb4218fa796e 100644
> --- a/arch/powerpc/platforms/powernv/opal-kmsg.c
> +++ b/arch/powerpc/platforms/powernv/opal-kmsg.c
> @@ -20,13 +20,13 @@
> * message, it just ensures that OPAL completely flushes the console buffer.
> */
> static void kmsg_dump_opal_console_flush(struct kmsg_dumper *dumper,
> - enum kmsg_dump_reason reason)
> + struct kmsg_dump_detail *detail)
> {
> /*
> * Outside of a panic context the pollers will continue to run,
> * so we don't need to do any special flushing.
> */
> - if (reason != KMSG_DUMP_PANIC)
> + if (detail->reason != KMSG_DUMP_PANIC)
> return;
>
> opal_flush_console(0);
> diff --git a/arch/um/kernel/kmsg_dump.c b/arch/um/kernel/kmsg_dump.c
> index 4382cf02a6d1..419021175272 100644
> --- a/arch/um/kernel/kmsg_dump.c
> +++ b/arch/um/kernel/kmsg_dump.c
> @@ -8,7 +8,7 @@
> #include <os.h>
>
> static void kmsg_dumper_stdout(struct kmsg_dumper *dumper,
> - enum kmsg_dump_reason reason)
> + struct kmsg_dump_detail *detail)
> {
> static struct kmsg_dump_iter iter;
> static DEFINE_SPINLOCK(lock);
> diff --git a/drivers/gpu/drm/drm_panic.c b/drivers/gpu/drm/drm_panic.c
> index 948aed00595e..8794c7f6c0ee 100644
> --- a/drivers/gpu/drm/drm_panic.c
> +++ b/drivers/gpu/drm/drm_panic.c
> @@ -655,11 +655,11 @@ static struct drm_plane *to_drm_plane(struct kmsg_dumper *kd)
> return container_of(kd, struct drm_plane, kmsg_panic);
> }
>
> -static void drm_panic(struct kmsg_dumper *dumper, enum kmsg_dump_reason reason)
> +static void drm_panic(struct kmsg_dumper *dumper, struct kmsg_dump_detail *detail)
> {
> struct drm_plane *plane = to_drm_plane(dumper);
>
> - if (reason == KMSG_DUMP_PANIC)
> + if (detail->reason == KMSG_DUMP_PANIC)
> draw_panic_plane(plane);
> }
>
> diff --git a/drivers/hv/hv_common.c b/drivers/hv/hv_common.c
> index 9c452bfbd571..7a35c82976e0 100644
> --- a/drivers/hv/hv_common.c
> +++ b/drivers/hv/hv_common.c
> @@ -207,13 +207,13 @@ static int hv_die_panic_notify_crash(struct notifier_block *self,
> * buffer and call into Hyper-V to transfer the data.
> */
> static void hv_kmsg_dump(struct kmsg_dumper *dumper,
> - enum kmsg_dump_reason reason)
> + struct kmsg_dump_detail *detail)
> {
> struct kmsg_dump_iter iter;
> size_t bytes_written;
>
> /* We are only interested in panics. */
> - if (reason != KMSG_DUMP_PANIC || !sysctl_record_panic_msg)
> + if (detail->reason != KMSG_DUMP_PANIC || !sysctl_record_panic_msg)
> return;
>
> /*
> diff --git a/drivers/mtd/mtdoops.c b/drivers/mtd/mtdoops.c
> index 2f11585b5613..86d49db9196d 100644
> --- a/drivers/mtd/mtdoops.c
> +++ b/drivers/mtd/mtdoops.c
> @@ -298,7 +298,7 @@ static void find_next_position(struct mtdoops_context *cxt)
> }
>
> static void mtdoops_do_dump(struct kmsg_dumper *dumper,
> - enum kmsg_dump_reason reason)
> + struct kmsg_dump_detail *detail)
> {
> struct mtdoops_context *cxt = container_of(dumper,
> struct mtdoops_context, dump);
> diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
> index 3497ede88aa0..9c6b7c97fa3c 100644
> --- a/fs/pstore/platform.c
> +++ b/fs/pstore/platform.c
> @@ -275,7 +275,7 @@ void pstore_record_init(struct pstore_record *record,
> * end of the buffer.
> */
> static void pstore_dump(struct kmsg_dumper *dumper,
> - enum kmsg_dump_reason reason)
> + struct kmsg_dump_detail *detail)
> {
> struct kmsg_dump_iter iter;
> unsigned long total = 0;
> @@ -285,9 +285,9 @@ static void pstore_dump(struct kmsg_dumper *dumper,
> int saved_ret = 0;
> int ret;
>
> - why = kmsg_dump_reason_str(reason);
> + why = kmsg_dump_reason_str(detail->reason);
>
> - if (pstore_cannot_block_path(reason)) {
> + if (pstore_cannot_block_path(detail->reason)) {
> if (!spin_trylock_irqsave(&psinfo->buf_lock, flags)) {
> pr_err("dump skipped in %s path because of concurrent dump\n",
> in_nmi() ? "NMI" : why);
> @@ -311,7 +311,7 @@ static void pstore_dump(struct kmsg_dumper *dumper,
> pstore_record_init(&record, psinfo);
> record.type = PSTORE_TYPE_DMESG;
> record.count = oopscount;
> - record.reason = reason;
> + record.reason = detail->reason;
> record.part = part;
> record.buf = psinfo->buf;
>
> @@ -352,7 +352,7 @@ static void pstore_dump(struct kmsg_dumper *dumper,
> }
>
> ret = psinfo->write(&record);
> - if (ret == 0 && reason == KMSG_DUMP_OOPS) {
> + if (ret == 0 && detail->reason == KMSG_DUMP_OOPS) {
> pstore_new_entry = 1;
> pstore_timer_kick();
> } else {
> diff --git a/include/linux/kmsg_dump.h b/include/linux/kmsg_dump.h
> index 906521c2329c..65f5a47727bc 100644
> --- a/include/linux/kmsg_dump.h
> +++ b/include/linux/kmsg_dump.h
> @@ -39,6 +39,17 @@ struct kmsg_dump_iter {
> u64 next_seq;
> };
>
> +/**
> + *struct kmsg_dump_detail - kernel crash detail
> + * @reason: reason for the crash, see kmsg_dump_reason.
> + * @description: optional short string, to provide additional information.
> + */
> +
> +struct kmsg_dump_detail {
> + enum kmsg_dump_reason reason;
> + const char *description;
> +};
> +
> /**
> * struct kmsg_dumper - kernel crash message dumper structure
> * @list: Entry in the dumper list (private)
> @@ -49,13 +60,13 @@ struct kmsg_dump_iter {
> */
> struct kmsg_dumper {
> struct list_head list;
> - void (*dump)(struct kmsg_dumper *dumper, enum kmsg_dump_reason reason);
> + void (*dump)(struct kmsg_dumper *dumper, struct kmsg_dump_detail *detail);
> enum kmsg_dump_reason max_reason;
> bool registered;
> };
>
> #ifdef CONFIG_PRINTK
> -void kmsg_dump(enum kmsg_dump_reason reason);
> +void kmsg_dump_desc(enum kmsg_dump_reason reason, const char *desc);
>
> bool kmsg_dump_get_line(struct kmsg_dump_iter *iter, bool syslog,
> char *line, size_t size, size_t *len);
> @@ -71,7 +82,7 @@ int kmsg_dump_unregister(struct kmsg_dumper *dumper);
>
> const char *kmsg_dump_reason_str(enum kmsg_dump_reason reason);
> #else
> -static inline void kmsg_dump(enum kmsg_dump_reason reason)
> +static inline void kmsg_dump_desc(enum kmsg_dump_reason reason, const char *desc)
> {
> }
>
> @@ -107,4 +118,9 @@ static inline const char *kmsg_dump_reason_str(enum kmsg_dump_reason reason)
> }
> #endif
>
> +static inline void kmsg_dump(enum kmsg_dump_reason reason)
> +{
> + kmsg_dump_desc(reason, NULL);
> +}
> +
> #endif /* _LINUX_KMSG_DUMP_H */
> diff --git a/kernel/panic.c b/kernel/panic.c
> index 0843a275531a..0a8b29c44f3c 100644
> --- a/kernel/panic.c
> +++ b/kernel/panic.c
> @@ -378,7 +378,7 @@ void panic(const char *fmt, ...)
>
> panic_print_sys_info(false);
>
> - kmsg_dump(KMSG_DUMP_PANIC);
> + kmsg_dump_desc(KMSG_DUMP_PANIC, buf);
>
> /*
> * If you doubt kdump always works fine in any situation,
> diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
> index 5dcc05e1aa56..19bc414be5f0 100644
> --- a/kernel/printk/printk.c
> +++ b/kernel/printk/printk.c
> @@ -4272,16 +4272,21 @@ const char *kmsg_dump_reason_str(enum kmsg_dump_reason reason)
> EXPORT_SYMBOL_GPL(kmsg_dump_reason_str);
>
> /**
> - * kmsg_dump - dump kernel log to kernel message dumpers.
> + * kmsg_dump_desc - dump kernel log to kernel message dumpers.
> * @reason: the reason (oops, panic etc) for dumping
> + * @desc: a short string to describe what caused the panic or oops. Can be NULL
> + * if no additional description is available.
> *
> * Call each of the registered dumper's dump() callback, which can
> * retrieve the kmsg records with kmsg_dump_get_line() or
> * kmsg_dump_get_buffer().
> */
> -void kmsg_dump(enum kmsg_dump_reason reason)
> +void kmsg_dump_desc(enum kmsg_dump_reason reason, const char *desc)
> {
> struct kmsg_dumper *dumper;
> + struct kmsg_dump_detail detail = {
> + .reason = reason,
> + .description = desc};
>
> rcu_read_lock();
> list_for_each_entry_rcu(dumper, &dump_list, list) {
> @@ -4299,7 +4304,7 @@ void kmsg_dump(enum kmsg_dump_reason reason)
> continue;
>
> /* invoke dumper which will iterate over records */
> - dumper->dump(dumper, reason);
> + dumper->dump(dumper, &detail);
> }
> rcu_read_unlock();
> }
>
> base-commit: 82e4255305c554b0bb18b7ccf2db86041b4c8b6e
Gentle ping, I need reviews from powerpc, usermod linux, mtd, pstore and
hyperv, to be able to push it in the drm-misc tree.
Best regards,
--
Jocelyn
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