kernel.git/drivers/oprofile/cpu_buffer.c, branch linux-2.6.32.y

oprofile: fix crash when accessing freed task structs

2010-09-20T20:17:50Z

commit 750d857c682f4db60d14722d430c7ccc35070962 upstream. This patch fixes a crash during shutdown reported below. The crash is caused by accessing already freed task structs. The fix changes the order for registering and unregistering notifier callbacks. All notifiers must be initialized before buffers start working. To stop buffer synchronization we cancel all workqueues, unregister the notifier callback and then flush all buffers. After all of this we finally can free all tasks listed. This should avoid accessing freed tasks. On 22.07.10 01:14:40, Benjamin Herrenschmidt wrote: > So the initial observation is a spinlock bad magic followed by a crash > in the spinlock debug code: > > [ 1541.586531] BUG: spinlock bad magic on CPU#5, events/5/136 > [ 1541.597564] Unable to handle kernel paging request for data at address 0x6b6b6b6b6b6b6d03 > > Backtrace looks like: > > spin_bug+0x74/0xd4 > ._raw_spin_lock+0x48/0x184 > ._spin_lock+0x10/0x24 > .get_task_mm+0x28/0x8c > .sync_buffer+0x1b4/0x598 > .wq_sync_buffer+0xa0/0xdc > .worker_thread+0x1d8/0x2a8 > .kthread+0xa8/0xb4 > .kernel_thread+0x54/0x70 > > So we are accessing a freed task struct in the work queue when > processing the samples. Reported-by: Benjamin Herrenschmidt Signed-off-by: Robert Richter Signed-off-by: Greg Kroah-Hartman

oprofile: remove double ring buffering

2010-07-05T18:10:27Z

commit cb6e943ccf19ab6d3189147e9d625a992e016084 upstream. oprofile used a double buffer scheme for its cpu event buffer to avoid races on reading with the old locked ring buffer. But that is obsolete now with the new ring buffer, so simply use a single buffer. This greatly simplifies the code and avoids a lot of sample drops on large runs, especially with call graph. Based on suggestions from Steven Rostedt For stable kernels from v2.6.32, but not earlier. Signed-off-by: Andi Kleen Cc: Steven Rostedt Signed-off-by: Robert Richter Signed-off-by: Greg Kroah-Hartman

x86/oprofile: introduce oprofile_add_data64()

2009-06-11T18:16:00Z

The IBS implemention writes 64 bit register values to the cpu buffer by writing two 32 values using oprofile_add_data(). This patch introduces oprofile_add_data64() to write a single 64 bit value to the buffer. Signed-off-by: Robert Richter

oprofile: remove obselete include headers

2009-06-11T14:10:12Z

This became obsolete with this commit: 6dad828 oprofile: port to the new ring_buffer Signed-off-by: Robert Richter

oprofile: fix cpu buffer size

2009-05-07T15:28:59Z

The unit of oprofile_cpu_buffer_size is in samples, but was allocated in bytes. This led to the allocation of too small cpu buffers. This patch recalculates the buffer size in bytes taking also the ring_buffer_event header size into account. Reported-by: Suravee Suthikulpanit Signed-off-by: Robert Richter

ring_buffer: remove unused flags parameter, fix

2009-02-06T00:14:05Z

Oprofile's ring-buffer use was not considered. Signed-off-by: Ingo Molnar

oprofile: fix uninitialized use of struct op_entry

2009-01-17T16:26:39Z

Impact: fix crash In case of losing samples struct op_entry could have been used uninitialized causing e.g. a wrong preemption count or NULL pointer access. This patch fixes this. Signed-off-by: Robert Richter Signed-off-by: Ingo Molnar

oprofile: make new cpu buffer functions part of the api

2009-01-07T21:48:15Z

This patch creates the new functions oprofile_write_reserve() oprofile_add_data() oprofile_write_commit() and makes them part of the oprofile api. Signed-off-by: Robert Richter

oprofile: remove #ifdef CONFIG_OPROFILE_IBS in non-ibs code

2009-01-07T21:47:56Z

The ifdefs can be removed since the code is no longer ibs specific and can be used for other purposes as well. IBS specific code is only in op_model_amd.c. Signed-off-by: Robert Richter

oprofile: use new data sample format for ibs

2009-01-07T21:47:23Z

The new ring buffer implementation allows the storage of samples with different size. This patch implements the usage of the new sample format to store ibs samples in the cpu buffer. Until now, writing to the cpu buffer could lead to incomplete sampling sequences since IBS samples were transfered in multiple samples. Due to a full buffer, data could be lost at any time. This can't happen any more since the complete data is reserved in advance and then stored in a single sample. Signed-off-by: Robert Richter