linux/kernel/trace/ring_buffer.c, branch v2.6.33

ring-buffer: Check for end of page in iterator

2010-01-26T21:14:08Z

If the iterator comes to an empty page for some reason, or if the page is emptied by a consuming read. The iterator code currently does not check if the iterator is pass the contents, and may return a false entry. This patch adds a check to the ring buffer iterator to test if the current page has been completely read and sets the iterator to the next page if necessary. Signed-off-by: Steven Rostedt

ring-buffer: Check if ring buffer iterator has stale data

2010-01-26T21:09:30Z

Usually reads of the ring buffer is performed by a single task. There are two types of reads from the ring buffer. One is a consuming read which will consume the entry that was read and the next read will be the entry that follows. The other is an iterator that will let the user read the contents of the ring buffer without modifying it. When an iterator is allocated, writes to the ring buffer are disabled to protect the iterator. The problem exists when consuming reads happen while an iterator is allocated. Specifically, the kind of read that swaps out an entire page (used by splice) and replaces it with a new read. If the iterator is on the page that is swapped out, then the next read may read from this swapped out page and return garbage. This patch adds a check when reading the iterator to make sure that the iterator contents are still valid. If a consuming read has taken place, the iterator is reset. Signed-off-by: Steven Rostedt

ring-buffer: Add rb_list_head() wrapper around new reader page next field

2010-01-07T01:40:44Z

If the very unlikely case happens where the writer moves the head by one between where the head page is read and where the new reader page is assigned _and_ the writer then writes and wraps the entire ring buffer so that the head page is back to what was originally read as the head page, the page to be swapped will have a corrupted next pointer. Simple solution is to wrap the assignment of the next pointer with a rb_list_head(). Signed-off-by: Steven Rostedt

ring-buffer: Wrap a list.next reference with rb_list_head()

2010-01-07T01:38:25Z

This reference at the end of rb_get_reader_page() was causing off-by-one writes to the prev pointer of the page after the reader page when that page is the head page, and therefore the reader page has the RB_PAGE_HEAD flag in its list.next pointer. This eventually results in a GPF in a subsequent call to rb_set_head_page() (usually from rb_get_reader_page()) when that prev pointer is dereferenced. The dereferenced register would characteristically have an address that appears shifted left by one byte (eg, ffxxxxxxxxxxxxyy instead of ffffxxxxxxxxxxxx) due to being written at an address one byte too high. Signed-off-by: David Sharp LKML-Reference: <1262826727-9090-1-git-send-email-dhsharp@google.com> Signed-off-by: Steven Rostedt

Merge branch 'tracing-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

2009-12-16T20:02:25Z

* 'tracing-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: tracing: Fix return of trace_dump_stack() ksym_tracer: Fix bad cast tracing/power: Remove two exports tracing: Change event->profile_count to be int type tracing: Simplify trace_option_write() tracing: Remove useless trace option tracing: Use seq file for trace_clock tracing: Use seq file for trace_options function-graph: Allow writing the same val to set_graph_function ftrace: Call trace_parser_clear() properly ftrace: Return EINVAL when writing invalid val to set_ftrace_filter tracing: Move a printk out of ftrace_raw_reg_event_foo() tracing: Pull up calls to trace_define_common_fields() tracing: Extract duplicate ftrace_raw_init_event_foo() ftrace.h: Use common pr_info fmt string tracing: Add stack trace to irqsoff tracer tracing: Add trace_dump_stack() ring-buffer: Move resize integrity check under reader lock ring-buffer: Use sync sched protection on ring buffer resizing tracing: Fix wrong usage of strstrip in trace_ksyms

locking: Convert __raw_spin* functions to arch_spin*

2009-12-14T22:55:32Z

Name space cleanup. No functional change. Signed-off-by: Thomas Gleixner Acked-by: Peter Zijlstra Acked-by: David S. Miller Acked-by: Ingo Molnar Cc: linux-arch@vger.kernel.org

locking: Rename __RAW_SPIN_LOCK_UNLOCKED to __ARCH_SPIN_LOCK_UNLOCKED

2009-12-14T22:55:32Z

Further name space cleanup. No functional change Signed-off-by: Thomas Gleixner Acked-by: Peter Zijlstra Acked-by: David S. Miller Acked-by: Ingo Molnar Cc: linux-arch@vger.kernel.org

locking: Convert raw_spinlock to arch_spinlock

2009-12-14T22:55:32Z

The raw_spin* namespace was taken by lockdep for the architecture specific implementations. raw_spin_* would be the ideal name space for the spinlocks which are not converted to sleeping locks in preempt-rt. Linus suggested to convert the raw_ to arch_ locks and cleanup the name space instead of using an artifical name like core_spin, atomic_spin or whatever No functional change. Signed-off-by: Thomas Gleixner Acked-by: Peter Zijlstra Acked-by: David S. Miller Acked-by: Ingo Molnar Cc: linux-arch@vger.kernel.org

ring-buffer: Move resize integrity check under reader lock

2009-12-11T04:20:52Z

While using an application that does splice on the ftrace ring buffer at start up, I triggered an integrity check failure. Looking into this, I discovered that resizing the buffer performs an integrity check after the buffer is resized. This check unfortunately is preformed after it releases the reader lock. If a reader is reading the buffer it may cause the integrity check to trigger a false failure. This patch simply moves the integrity checker under the protection of the ring buffer reader lock. Signed-off-by: Steven Rostedt

ring-buffer: Use sync sched protection on ring buffer resizing

2009-12-11T03:54:27Z

There was a comment in the ring buffer code that says the calling layers should prevent tracing or reading of the ring buffer while resizing. I have discovered that the tracers do not honor this arrangement. This patch moves the disabling and synchronizing the ring buffer to a higher layer during resizing. This guarantees that no writes are occurring while the resize takes place. Signed-off-by: Steven Rostedt