user/sven/linux.git/include/linux/pstore.h, branch v3.14.29

pstore: Don't allow high traffic options on fragile devices

2013-12-20T21:12:01Z

Some pstore backing devices use on board flash as persistent storage. These have limited numbers of write cycles so it is a poor idea to use them from high frequency operations. Signed-off-by: Tony Luck Signed-off-by: Linus Torvalds

pstore: Introduce new argument 'compressed' in the read callback

2013-08-19T17:18:11Z

Backends will set the flag 'compressed' after reading the log from persistent store to indicate the data being returned to pstore is compressed or not. Signed-off-by: Aruna Balakrishnaiah Reviewed-by: Kees Cook Signed-off-by: Tony Luck

pstore: Add new argument 'compressed' in pstore write callback

2013-08-19T17:18:10Z

Addition of new argument 'compressed' in the write call back will help the backend to know if the data passed from pstore is compressed or not (In case where compression fails.). If compressed, the backend can add a tag indicating the data is compressed while writing to persistent store. Signed-off-by: Aruna Balakrishnaiah Reviewed-by: Kees Cook Signed-off-by: Tony Luck

pstore: Pass header size in the pstore write callback

2013-07-01T08:10:48Z

Header size is needed to distinguish between header and the dump data. Incorporate the addition of new argument (hsize) in the pstore write callback. Signed-off-by: Aruna Balakrishnaiah Acked-by: Kees Cook Signed-off-by: Benjamin Herrenschmidt

powerpc/pseries: Read common partition via pstore

2013-06-20T07:05:02Z

This patch exploits pstore subsystem to read details of common partition in NVRAM to a separate file in /dev/pstore. For instance, common partition details will be stored in a file named [common-nvram-6]. Signed-off-by: Aruna Balakrishnaiah Reviewed-by: Jim Keniston Signed-off-by: Benjamin Herrenschmidt

powerpc/pseries: Read of-config partition via pstore

2013-06-20T07:04:59Z

This patch set exploits the pstore subsystem to read details of of-config partition in NVRAM to a separate file in /dev/pstore. For instance, of-config partition details will be stored in a file named [of-nvram-5]. Signed-off-by: Aruna Balakrishnaiah Reviewed-by: Jim Keniston Signed-off-by: Benjamin Herrenschmidt

powerpc/pseries: Read rtas partition via pstore

2013-06-20T07:04:52Z

This patch set exploits the pstore subsystem to read details of rtas partition in NVRAM to a separate file in /dev/pstore. For instance, rtas details will be stored in a file named [rtas-nvram-4]. Signed-off-by: Aruna Balakrishnaiah Reviewed-by: Jim Keniston Signed-off-by: Benjamin Herrenschmidt

pstore: Avoid deadlock in panic and emergency-restart path

2013-01-11T18:20:50Z

[Issue] When pstore is in panic and emergency-restart paths, it may be blocked in those paths because it simply takes spin_lock. This is an example scenario which pstore may hang up in a panic path: - cpuA grabs psinfo->buf_lock - cpuB panics and calls smp_send_stop - smp_send_stop sends IRQ to cpuA - after 1 second, cpuB gives up on cpuA and sends an NMI instead - cpuA is now in an NMI handler while still holding buf_lock - cpuB is deadlocked This case may happen if a firmware has a bug and cpuA is stuck talking with it more than one second. Also, this is a similar scenario in an emergency-restart path: - cpuA grabs psinfo->buf_lock and stucks in a firmware - cpuB kicks emergency-restart via either sysrq-b or hangcheck timer. And then, cpuB is deadlocked by taking psinfo->buf_lock again. [Solution] This patch avoids the deadlocking issues in both panic and emergency_restart paths by introducing a function, is_non_blocking_path(), to check if a cpu can be blocked in current path. With this patch, pstore is not blocked even if another cpu has taken a spin_lock, in those paths by changing from spin_lock_irqsave to spin_trylock_irqsave. In addition, according to a comment of emergency_restart() in kernel/sys.c, spin_lock shouldn't be taken in an emergency_restart path to avoid deadlock. This patch fits the comment below. /** * emergency_restart - reboot the system * * Without shutting down any hardware or taking any locks * reboot the system. This is called when we know we are in * trouble so this is our best effort to reboot. This is * safe to call in interrupt context. */ void emergency_restart(void) Signed-off-by: Seiji Aguchi Acked-by: Don Zickus Signed-off-by: Tony Luck

efi_pstore: Add a sequence counter to a variable name

2012-11-27T00:07:44Z

[Issue] Currently, a variable name, which identifies each entry, consists of type, id and ctime. But if multiple events happens in a short time, a second/third event may fail to log because efi_pstore can't distinguish each event with current variable name. [Solution] A reasonable way to identify all events precisely is introducing a sequence counter to the variable name. The sequence counter has already supported in a pstore layer with "oopscount". So, this patch adds it to a variable name. Also, it is passed to read/erase callbacks of platform drivers in accordance with the modification of the variable name. a variable name of first event: dump-type0-1-12345678 a variable name of second event: dump-type0-1-12345678 type:0 id:1 ctime:12345678 If multiple events happen in a short time, efi_pstore can't distinguish them because variable names are same among them. it can be distinguishable by adding a sequence counter as follows. a variable name of first event: dump-type0-1-1-12345678 a variable name of Second event: dump-type0-1-2-12345678 type:0 id:1 sequence counter: 1(first event), 2(second event) ctime:12345678 In case of a write callback executed in pstore_console_write(), "0" is added to an argument of the write callback because it just logs all kernel messages and doesn't need to care about multiple events. Signed-off-by: Seiji Aguchi Acked-by: Rafael J. Wysocki Acked-by: Mike Waychison Signed-off-by: Tony Luck

efi_pstore: Add ctime to argument of erase callback

2012-11-27T00:02:12Z

[Issue] Currently, a variable name, which is used to identify each log entry, consists of type, id and ctime. But an erase callback does not use ctime. If efi_pstore supported just one log, type and id were enough. However, in case of supporting multiple logs, it doesn't work because it can't distinguish each entry without ctime at erasing time. As you can see below, efi_pstore can't differentiate first event from second one without ctime. a variable name of first event: dump-type0-1-12345678 a variable name of second event: dump-type0-1-23456789 type:0 id:1 ctime:12345678, 23456789 [Solution] This patch adds ctime to an argument of an erase callback. It works across reboots because ctime of pstore means the date that the record was originally stored. To do this, efi_pstore saves the ctime to variable name at writing time and passes it to pstore at reading time. Signed-off-by: Seiji Aguchi Acked-by: Mike Waychison Signed-off-by: Tony Luck