Re: [PATCH v3 05/11] pstore/blk: blkoops: support console recorder

From: WeiXiong Liao
Date: Mon Apr 13 2020 - 22:13:22 EST

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Hi Kees Cook,

A bad subject on patch 5 and patch 6 that "blkoops" should be "pstore/zone".

I will fix it in the next version.

On 2020/3/25 PM 4:55, WeiXiong Liao wrote:
> Support recorder for console. To enable console recorder, just make
> console_size be greater than 0 and a multiple of 4096.
>
> Signed-off-by: WeiXiong Liao <liaoweixiong@xxxxxxxxxxxxxxxxx>
> ---
> fs/pstore/Kconfig | 12 ++++++++
> fs/pstore/pstore_blk.c | 12 +++++++-
> fs/pstore/pstore_zone.c | 70 +++++++++++++++++++++++++++++++++++++++++----
> include/linux/pstore_zone.h | 4 ++-
> 4 files changed, 91 insertions(+), 7 deletions(-)
>
> diff --git a/fs/pstore/Kconfig b/fs/pstore/Kconfig
> index 8cead860dcfc..bf90de48ad3c 100644
> --- a/fs/pstore/Kconfig
> +++ b/fs/pstore/Kconfig
> @@ -225,6 +225,18 @@ config PSTORE_BLK_PMSG_SIZE
> NOTE that, both Kconfig and module parameters can configure
> pstore/blk, but module parameters have priority over Kconfig.
>
> +config PSTORE_BLK_CONSOLE_SIZE
> + int "Size in Kbytes of console to store"
> + depends on PSTORE_BLK
> + depends on PSTORE_CONSOLE
> + default 64
> + help
> + This just sets size of console (console_size) for pstore/blk. The
> + size is in KB and must be a multiple of 4.
> +
> + NOTE that, both Kconfig and module parameters can configure
> + pstore/blk, but module parameters have priority over Kconfig.
> +
> config PSTORE_BLK_DUMP_OOPS
> bool "dump oops"
> depends on PSTORE_BLK
> diff --git a/fs/pstore/pstore_blk.c b/fs/pstore/pstore_blk.c
> index 85cd9f2335be..2b513acaa18f 100644
> --- a/fs/pstore/pstore_blk.c
> +++ b/fs/pstore/pstore_blk.c
> @@ -26,6 +26,14 @@
> module_param(pmsg_size, long, 0400);
> MODULE_PARM_DESC(pmsg_size, "pmsg size in kbytes");
>
> +#if IS_ENABLED(CONFIG_PSTORE_CONSOLE)
> +static long console_size = CONFIG_PSTORE_BLK_CONSOLE_SIZE;
> +#else
> +static long console_size = -1;
> +#endif
> +module_param(console_size, long, 0400);
> +MODULE_PARM_DESC(console_size, "console size in kbytes");
> +
> static int dump_oops = CONFIG_PSTORE_BLK_DUMP_OOPS;
> module_param(dump_oops, int, 0400);
> MODULE_PARM_DESC(total_size, "whether dump oops");
> @@ -81,7 +89,8 @@
> * whole disk).
> * On success, the number of bytes should be returned, others
> * means error.
> - * @write: The same as @read.
> + * @write: The same as @read, but the following error number:
> + * -EBUSY means try to write again later.
> * @panic_write:The write operation only used for panic case. It's optional
> * if you do not care panic log. The parameters and return value
> * are the same as @read.
> @@ -131,6 +140,7 @@ static int psblk_register_do(struct psblk_device *dev)
>
> verify_size(oops_size, 4096, dev->flags & PSTORE_FLAGS_DMESG);
> verify_size(pmsg_size, 4096, dev->flags & PSTORE_FLAGS_PMSG);
> + verify_size(console_size, 4096, dev->flags & PSTORE_FLAGS_CONSOLE);
> #undef verify_size
> dump_oops = dump_oops <= 0 ? 0 : 1;
>
> diff --git a/fs/pstore/pstore_zone.c b/fs/pstore/pstore_zone.c
> index 444bce7f9ac3..e1e84505b046 100644
> --- a/fs/pstore/pstore_zone.c
> +++ b/fs/pstore/pstore_zone.c
> @@ -87,10 +87,12 @@ struct psz_zone {
> *
> * @opszs: oops/panic storage zones
> * @ppsz: pmsg storage zone
> + * @cpsz: console storage zone
> * @oops_max_cnt: max count of @opszs
> * @oops_read_cnt: counter to read oops zone
> * @oops_write_cnt: counter to write
> * @pmsg_read_cnt: counter to read pmsg zone
> + * @console_read_cnt: counter to read console zone
> * @oops_counter: counter to oops
> * @panic_counter: counter to panic
> * @recovered: whether finish recovering data from storage
> @@ -102,10 +104,12 @@ struct psz_zone {
> struct psz_context {
> struct psz_zone **opszs;
> struct psz_zone *ppsz;
> + struct psz_zone *cpsz;
> unsigned int oops_max_cnt;
> unsigned int oops_read_cnt;
> unsigned int oops_write_cnt;
> unsigned int pmsg_read_cnt;
> + unsigned int console_read_cnt;
> /*
> * the counter should be recovered when recover.
> * It records the oops/panic times after burning rather than booting.
> @@ -125,6 +129,9 @@ struct psz_context {
> };
> static struct psz_context psz_cxt;
>
> +static void psz_flush_all_dirty_zones(struct work_struct *> +static DECLARE_WORK(psz_cleaner, psz_flush_all_dirty_zones);

I think it's better to use delayed work.

static DECLARE_DELAYED_WORK(psz_cleaner, psz_flush_all_dirty_zones);

> +
> /**
> * enum psz_flush_mode - flush mode for psz_zone_write()
> *
> @@ -235,6 +242,9 @@ static int psz_zone_write(struct psz_zone *zone,
> return 0;
> dirty:
> atomic_set(&zone->dirty, true);
> + /* flush dirty zones nicely */
> + if (wcnt == -EBUSY && !is_on_panic())
> + schedule_work(&psz_cleaner);

Change to:

schedule_delayed_work(&psz_cleaner, msecs_to_jiffies(500));

delay for 500ms to merge more log of console and reduce calling times.

> return -EBUSY;
> }
>
> @@ -291,6 +301,15 @@ static int psz_move_zone(struct psz_zone *old, struct psz_zone *new)
> return 0;
> }
>
> +static void psz_flush_all_dirty_zones(struct work_struct *work)
> +{
> + struct psz_context *cxt = &psz_cxt;
> +
> + psz_flush_dirty_zone(cxt->ppsz);
> + psz_flush_dirty_zone(cxt->cpsz);
> + psz_flush_dirty_zones(cxt->opszs, cxt->oops_max_cnt);
> +}

If flush dirty failed, I think it should try again later.

int ret = 0;

ret |= psz_flush_dirty_zone(cxt->ppsz);
ret |= psz_flush_dirty_zone(cxt->cpsz);
ret |= psz_flush_dirty_zones(cxt->opszs, cxt->oops_max_cnt);
if (ret)
schedule_delayed_work(&psz_cleaner, msecs_to_jiffies(1000));

I will fix it in the next version.

> +
> static int psz_recover_oops_data(struct psz_context *cxt)
> {
> struct psz_info *info = cxt->psz_info;
> @@ -546,6 +565,10 @@ static inline int psz_recovery(struct psz_context *cxt)
> if (ret)
> goto recover_fail;
>
> + ret = psz_recover_zone(cxt, cxt->cpsz);
> + if (ret)
> + goto recover_fail;
> +
> pr_debug("recover end!\n");
> atomic_set(&cxt->recovered, 1);
> return 0;
> @@ -561,6 +584,7 @@ static int psz_pstore_open(struct pstore_info *psi)
>
> cxt->oops_read_cnt = 0;
> cxt->pmsg_read_cnt = 0;
> + cxt->console_read_cnt = 0;
> return 0;
> }
>
> @@ -625,8 +649,9 @@ static int psz_pstore_erase(struct pstore_record *record)
> return psz_oops_erase(cxt, cxt->opszs[record->id], record);
> case PSTORE_TYPE_PMSG:
> return psz_record_erase(cxt, cxt->ppsz);
> - default:
> - return -EINVAL;
> + case PSTORE_TYPE_CONSOLE:
> + return psz_record_erase(cxt, cxt->cpsz);
> + default: return -EINVAL;
> }
> }
>
> @@ -767,9 +792,18 @@ static int notrace psz_pstore_write(struct pstore_record *record)
> record->reason == KMSG_DUMP_PANIC)
> atomic_set(&cxt->on_panic, 1);
>
> + /*
> + * if on panic, do not write except panic records
> + * Fix case that panic_write prints log which wakes up console recorder.
> + */
> + if (is_on_panic() && record->type != PSTORE_TYPE_DMESG)
> + return -EBUSY;
> +
> switch (record->type) {
> case PSTORE_TYPE_DMESG:
> return psz_oops_write(cxt, record);
> + case PSTORE_TYPE_CONSOLE:
> + return psz_record_write(cxt->cpsz, record);
> case PSTORE_TYPE_PMSG:
> return psz_record_write(cxt->ppsz, record);
> default:
> @@ -794,6 +828,13 @@ static struct psz_zone *psz_read_next_zone(struct psz_context *cxt)
> return zone;
> }
>
> + if (cxt->console_read_cnt == 0) {
> + cxt->console_read_cnt++;
> + zone = cxt->cpsz;
> + if (psz_old_ok(zone))
> + return zone;
> + }
> +
> return NULL;
> }
>
> @@ -903,6 +944,8 @@ static ssize_t psz_pstore_read(struct pstore_record *record)
> readop = psz_oops_read;
> record->id = cxt->oops_read_cnt - 1;
> break;
> + case PSTORE_TYPE_CONSOLE:
> + fallthrough;
> case PSTORE_TYPE_PMSG:
> readop = psz_record_read;
> break;
> @@ -1050,6 +1093,8 @@ static void psz_free_all_zones(struct psz_context *cxt)
> psz_free_zones(&cxt->opszs, &cxt->oops_max_cnt);
> if (cxt->ppsz)
> psz_free_zone(&cxt->ppsz);
> + if (cxt->cpsz)
> + psz_free_zone(&cxt->cpsz);
> }
>
> static int psz_alloc_zones(struct psz_context *cxt)
> @@ -1066,6 +1111,14 @@ static int psz_alloc_zones(struct psz_context *cxt)
> goto free_out;
> }
>
> + off_size += info->console_size;
> + cxt->cpsz = psz_init_zone(PSTORE_TYPE_CONSOLE, &off,
> + info->console_size);
> + if (IS_ERR(cxt->cpsz)) {
> + err = PTR_ERR(cxt->cpsz);
> + goto free_out;
> + }
> +
> cxt->opszs = psz_init_zones(PSTORE_TYPE_DMESG, &off,
> info->total_size - off_size,
> info->oops_size, &cxt->oops_max_cnt);
> @@ -1100,7 +1153,7 @@ int psz_register(struct psz_info *info)
> return -EINVAL;
> }
>
> - if (!info->oops_size && !info->pmsg_size) {
> + if (!info->oops_size && !info->pmsg_size && !info->console_size) {
> pr_warn("at least one of the records be non-zero\n");
> return -EINVAL;
> }
> @@ -1128,6 +1181,7 @@ int psz_register(struct psz_info *info)
> check_size(total_size, 4096);
> check_size(oops_size, SECTOR_SIZE);
> check_size(pmsg_size, SECTOR_SIZE);
> + check_size(console_size, SECTOR_SIZE);
>
> #undef check_size
>
> @@ -1160,6 +1214,7 @@ int psz_register(struct psz_info *info)
> pr_debug("\ttotal size : %ld Bytes\n", info->total_size);
> pr_debug("\toops size : %ld Bytes\n", info->oops_size);
> pr_debug("\tpmsg size : %ld Bytes\n", info->pmsg_size);
> + pr_debug("\tconsole size : %ld Bytes\n", info->console_size);
>
> err = psz_alloc_zones(cxt);
> if (err) {
> @@ -1181,11 +1236,14 @@ int psz_register(struct psz_info *info)
> cxt->pstore.flags |= PSTORE_FLAGS_DMESG;
> if (info->pmsg_size)
> cxt->pstore.flags |= PSTORE_FLAGS_PMSG;
> + if (info->console_size)
> + cxt->pstore.flags |= PSTORE_FLAGS_CONSOLE;
>
> - pr_info("Registered %s as pszone backend for%s%s%s\n", info->name,
> + pr_info("Registered %s as pszone backend for%s%s%s%s\n", info->name,
> cxt->opszs && cxt->psz_info->dump_oops ? " Oops" : "",
> cxt->opszs && cxt->psz_info->panic_write ? " Panic" : "",
> - cxt->ppsz ? " Pmsg" : "");
> + cxt->ppsz ? " Pmsg" : "",
> + cxt->cpsz ? " Console" : "");
>
> err = pstore_register(&cxt->pstore);
> if (err) {
> @@ -1219,6 +1277,8 @@ void psz_unregister(struct psz_info *info)
> {
> struct psz_context *cxt = &psz_cxt;
>
> + flush_work(&psz_cleaner);

I think it should try to flush dirty zones before unregister.

psz_flush_all_dirty_zones(NULL);
flush_delayed_work(&psz_cleaner);

> +
> pstore_unregister(&cxt->pstore);
> kfree(cxt->pstore.buf);
> cxt->pstore.bufsize = 0;
> diff --git a/include/linux/pstore_zone.h b/include/linux/pstore_zone.h
> index 85e159d8f935..8a1838633010 100644
> --- a/include/linux/pstore_zone.h
> +++ b/include/linux/pstore_zone.h
> @@ -17,12 +17,13 @@
> * @oops_size: The size of oops/panic zone. Zero means disabled, otherwise,
> * it must be multiple of SECTOR_SIZE(512 Bytes).
> * @pmsg_size: The size of pmsg zone which is the same as @oops_size.
> + * @console_size:The size of console zone which is the same as @oops_size.
> * @dump_oops: Whether to dump oops log.
> * @read: The general read operation. Both of the function parameters
> * @size and @offset are relative value to storage.
> * On success, the number of bytes should be returned, others
> * means error.
> - * @write: The same as @read.
> + * @write: The same as @read, but -EBUSY means try to write again later.
> * @panic_write:The write operation only used for panic case. It's optional
> * if you do not care panic log. The parameters and return value
> * are the same as @read.
> @@ -34,6 +35,7 @@ struct psz_info {
> unsigned long total_size;
> unsigned long oops_size;
> unsigned long pmsg_size;
> + unsigned long console_size;
> int dump_oops;
> psz_read_op read;
> psz_write_op write;
>

--
WeiXiong Liao

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