Re: Ticketing spinlocks - How to get to the owner who locked the spinlock?
Hi Manty, On Tue, Jan 27, 2015 at 11:52 AM, manty kuma <mantykuma@gmail.com> wrote:
Dear Arun,
typedef struct raw_spinlock { arch_spinlock_t raw_lock; #ifdef CONFIG_GENERIC_LOCKBREAK unsigned int break_lock; #endif #ifdef CONFIG_DEBUG_SPINLOCK unsigned int magic, owner_cpu; void *owner; #endif #ifdef CONFIG_DEBUG_LOCK_ALLOC struct lockdep_map dep_map; #endif } raw_spinlock_t;
Unfortunately, CONFIG_DEBUG_SPINLOCK is disabled on my sw. So i do not have this information. :(
Any other way? What is the output from your runq command?
Thanks, Arun
On Tue, Jan 27, 2015 at 3:12 PM, Arun KS <getarunks@gmail.com> wrote:
Hello Manty,
On Tue, Jan 27, 2015 at 11:27 AM, manty kuma <mantykuma@gmail.com> wrote:
Hi All,
Currently I am looking into an issue which is holding the printk lock(logbuf_lock)
logbuf_lock = { raw_lock = { owner = 0, next = 4 } }
I read about ticketing spinlocks to understand the above output. I understood that 4 cpu's are waiting for the lock while someone already has it.
I would like to know who has it? Is there a way I can know which process is acquiring a given spinlock? Is the information not stored in it?
I am using crash tool to analyse the dump
crash> raw_spinlock_t typedef struct raw_spinlock { arch_spinlock_t raw_lock; unsigned int magic; unsigned int owner_cpu; void *owner; } raw_spinlock_t; SIZE: 16
The owner field points to task holding the lock, if locked.
Here is what i have in one of my dumps, crash> logbuf_lock logbuf_lock = $6 = { raw_lock = { { slock = 464001960, tickets = { owner = 7080, next = 7080 } } }, magic = 3735899821, owner_cpu = 4294967295, owner = 0xffffffff }
since lock is not acquired, it shows 0xFFFFFFFF. Otherwise point to a task_struct *.
thanks, Arun
Regards, Manty
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7 swappers and one process with name doe:handler In pawapper processes aswell, when i see the backtrace i see some mem aborts but couldnot get to the place which is holding the lock On Tuesday, January 27, 2015, Arun KS <getarunks@gmail.com> wrote:
Hi Manty,
On Tue, Jan 27, 2015 at 11:52 AM, manty kuma <mantykuma@gmail.com <javascript:;>> wrote:
Dear Arun,
typedef struct raw_spinlock { arch_spinlock_t raw_lock; #ifdef CONFIG_GENERIC_LOCKBREAK unsigned int break_lock; #endif #ifdef CONFIG_DEBUG_SPINLOCK unsigned int magic, owner_cpu; void *owner; #endif #ifdef CONFIG_DEBUG_LOCK_ALLOC struct lockdep_map dep_map; #endif } raw_spinlock_t;
Unfortunately, CONFIG_DEBUG_SPINLOCK is disabled on my sw. So i do not have this information. :(
Any other way? What is the output from your runq command?
Thanks, Arun
On Tue, Jan 27, 2015 at 3:12 PM, Arun KS <getarunks@gmail.com
<javascript:;>> wrote:
Hello Manty,
On Tue, Jan 27, 2015 at 11:27 AM, manty kuma <mantykuma@gmail.com
<javascript:;>> wrote:
Hi All,
Currently I am looking into an issue which is holding the printk lock(logbuf_lock)
logbuf_lock = { raw_lock = { owner = 0, next = 4 } }
I read about ticketing spinlocks to understand the above output. I understood that 4 cpu's are waiting for the lock while someone
already has
it.
I would like to know who has it? Is there a way I can know which process is acquiring a given spinlock? Is the information not stored in it?
I am using crash tool to analyse the dump
crash> raw_spinlock_t typedef struct raw_spinlock { arch_spinlock_t raw_lock; unsigned int magic; unsigned int owner_cpu; void *owner; } raw_spinlock_t; SIZE: 16
The owner field points to task holding the lock, if locked.
Here is what i have in one of my dumps, crash> logbuf_lock logbuf_lock = $6 = { raw_lock = { { slock = 464001960, tickets = { owner = 7080, next = 7080 } } }, magic = 3735899821, owner_cpu = 4294967295, owner = 0xffffffff }
since lock is not acquired, it shows 0xFFFFFFFF. Otherwise point to a task_struct *.
thanks, Arun
Regards, Manty
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