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2023-01-03docs: gdbmacros: print newest recordJohn Ogness1-1/+1
@head_id points to the newest record, but the printing loop exits when it increments to this value (before printing). Exit the printing loop after the newest record has been printed. The python-based function in scripts/gdb/linux/dmesg.py already does this correctly. Fixes: e60768311af8 ("scripts/gdb: update for lockless printk ringbuffer") Cc: stable@vger.kernel.org Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20221229134339.197627-1-john.ogness@linutronix.de
2020-09-22printk: move dictionary keys to dev_printk_infoJohn Ogness1-40/+33
Dictionaries are only used for SUBSYSTEM and DEVICE properties. The current implementation stores the property names each time they are used. This requires more space than otherwise necessary. Also, because the dictionary entries are currently considered optional, it cannot be relied upon that they are always available, even if the writer wanted to store them. These issues will increase should new dictionary properties be introduced. Rather than storing the subsystem and device properties in the dict ring, introduce a struct dev_printk_info with separate fields to store only the property values. Embed this struct within the struct printk_info to provide guaranteed availability. Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/87mu1jl6ne.fsf@jogness.linutronix.de
2020-09-15printk: ringbuffer: add finalization/extension supportJohn Ogness1-1/+2
Add support for extending the newest data block. For this, introduce a new finalization state (desc_finalized) denoting a committed descriptor that cannot be extended. Until a record is finalized, a writer can reopen that record to append new data. Reopening a record means transitioning from the desc_committed state back to the desc_reserved state. A writer can explicitly finalize a record if there is no intention of extending it. Also, records are automatically finalized when a new record is reserved. This relieves writers of needing to explicitly finalize while also making such records available to readers sooner. (Readers can only traverse finalized records.) Four new memory barrier pairs are introduced. Two of them are insignificant additions (data_realloc:A/desc_read:D and data_realloc:A/data_push_tail:B) because they are alternate path memory barriers that exactly match the purpose, pairing, and context of the two existing memory barrier pairs they provide an alternate path for. The other two new memory barrier pairs are significant additions: desc_reopen_last:A / _prb_commit:B - When reopening a descriptor, ensure the state transitions back to desc_reserved before fully trusting the descriptor data. _prb_commit:B / desc_reserve:D - When committing a descriptor, ensure the state transitions to desc_committed before checking the head ID to see if the descriptor needs to be finalized. Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20200914123354.832-6-john.ogness@linutronix.de
2020-09-15printk: ringbuffer: change representation of statesJohn Ogness1-4/+8
Rather than deriving the state by evaluating bits within the flags area of the state variable, assign the states explicit values and set those values in the flags area. Introduce macros to make it simple to read and write state values for the state variable. Although the functionality is preserved, the binary representation for the states is changed. Signed-off-by: John Ogness <john.ogness@linutronix.de> Reviewed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20200914123354.832-5-john.ogness@linutronix.de
2020-09-08scripts/gdb: update for lockless printk ringbufferJohn Ogness1-46/+107
With the introduction of the lockless printk ringbuffer, the data structure for the kernel log buffer was changed. Update the gdb scripts to be able to parse/print the new log buffer structure. Fixes: 896fbe20b4e2333fb55 ("printk: use the lockless ringbuffer") Signed-off-by: John Ogness <john.ogness@linutronix.de> Reported-by: Nick Desaulniers <ndesaulniers@google.com> Tested-by: Nick Desaulniers <ndesaulniers@google.com> Tested-by: Petr Mladek <pmladek@suse.com> [akpm@linux-foundation.org: A typo fix.] Signed-off-by: Petr Mladek <pmladek@suse.com> Link: https://lore.kernel.org/r/20200814212525.6118-3-john.ogness@linutronix.de
2019-07-15docs: admin-guide: add kdump documentation into itMauro Carvalho Chehab1-0/+264
The Kdump documentation describes procedures with admins use in order to solve issues on their systems. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>