summaryrefslogtreecommitdiffstats
path: root/kernel/trace/trace_printk.c
AgeCommit message (Collapse)Author
2012-04-23tracing: Add percpu buffers for trace_printk()Steven Rostedt
Currently, trace_printk() uses a single buffer to write into to calculate the size and format needed to save the trace. To do this safely in an SMP environment, a spin_lock() is taken to only allow one writer at a time to the buffer. But this could also affect what is being traced, and add synchronization that would not be there otherwise. Ideally, using percpu buffers would be useful, but since trace_printk() is only used in development, having per cpu buffers for something never used is a waste of space. Thus, the use of the trace_bprintk() format section is changed to be used for static fmts as well as dynamic ones. Then at boot up, we can check if the section that holds the trace_printk formats is non-empty, and if it does contain something, then we know a trace_printk() has been added to the kernel. At this time the trace_printk per cpu buffers are allocated. A check is also done at module load time in case a module is added that contains a trace_printk(). Once the buffers are allocated, they are never freed. If you use a trace_printk() then you should know what you are doing. A buffer is made for each type of context: normal softirq irq nmi The context is checked and the appropriate buffer is used. This allows for totally lockless usage of trace_printk(), and they no longer even disable interrupts. Requested-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2011-08-10tracing: Clean up tb_fmt to not give faulty compile warningSteven Rostedt
gcc incorrectly states that the variable "fmt" is uninitialized when CC_OPITMIZE_FOR_SIZE is set. Instead of just blindly setting fmt to NULL, the code is cleaned up a little to be a bit easier for humans to follow, as well as gcc to know the variables are initialized. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2011-06-09tracing: Fix regression in printk_formats fileSteven Rostedt
The fix to fix the printk_formats of modules broke the printk_formats of trace_printks in the kernel. The update of what to show via the seq_file was only updated if the passed in fmt was NULL, which happens only on the first iteration. The result was showing the first format every time instead of iterating through the available formats. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2011-04-04tracing: Print trace_bprintk() formats for modules tooSteven Rostedt
The file debugfs/tracing/printk_formats maps the addresses to the formats that are used by trace_bprintk() so that userspace tools can read the buffer and be able to decode trace_bprintk events to get the format saved when reading the ring buffer directly. This is because trace_bprintk() does not store the format into the buffer, but just the address of the format, which is hidden in the kernel memory. But currently it only exports trace_bprintk()s from the kernel core and not for modules. The modules need their formats exported as well. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2011-04-04tracing: Convert trace_printk() formats for module to const char *Steven Rostedt
The trace_printk() formats for modules do not show up in the debugfs/tracing/printk_formats file. Only the formats that are for trace_printk()s that are in the kernel core. To facilitate the change to add trace_printk() formats from modules into that file as well, we need to convert the structure that holds the formats from char fmt[], into const char *fmt, and allocate them separately. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2009-09-18tracing: Remove markersChristoph Hellwig
Now that the last users of markers have migrated to the event tracer we can kill off the (now orphan) support code. Signed-off-by: Christoph Hellwig <hch@lst.de> Acked-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Frederic Weisbecker <fweisbec@gmail.com> LKML-Reference: <20090917173527.GA1699@lst.de> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-07-23tracing: show proper address for trace-printk formatSteven Rostedt
Since the trace_printk may use pointers to the format fields in the buffer, they are exported via debugfs/tracing/printk_formats. This is used by utilities that read the ring buffer in binary format. It helps the utilities map the address of the format in the binary buffer to what the printf format looks like. Unfortunately, the way the output code works, it exports the address of the pointer to the format address, and not the format address itself. This makes the file totally useless in trying to figure out what format string a binary address belongs to. Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2009-06-24tracing_bprintk: Don't increment @pos in t_start()Li Zefan
It's wrong to increment @pos in t_start(), otherwise we'll lose some entries when reading printk_formats, if the output is larger than PAGE_SIZE. Reported-by: Lai Jiangshan <laijs@cn.fujitsu.com> Reviewed-by: Liming Wang <liming.wang@windriver.com> Signed-off-by: Li Zefan <lizf@cn.fujitsu.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Frederic Weisbecker <fweisbec@gmail.com> LKML-Reference: <4A4186FA.1020106@cn.fujitsu.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-04-07tracing/ftrace: factorize the tracing files creationFrederic Weisbecker
Impact: cleanup Most of the tracing files creation follow the same pattern: ret = debugfs_create_file(...) if (!ret) pr_warning("Couldn't create ... entry\n") Unify it! Reported-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> LKML-Reference: <1238109938-11840-1-git-send-email-fweisbec@gmail.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2009-03-19tracing: remove recording function depth from trace_printkSteven Rostedt
The function depth in trace_printk was to facilitate the function graph output. Now that the function graph calculates the depth within the trace output, we no longer need to record the depth when the trace_printk is called. Signed-off-by: Steven Rostedt <srostedt@redhat.com>
2009-03-12tracing: export trace formats to user spaceSteven Rostedt
The binary printk saves a pointer to the format string in the ring buffer. On output, the format is processed. But if the user is reading the ring buffer through a binary interface, the pointer is meaningless. This patch creates a file called printk_formats that maps the pointers to the formats. # cat /debug/tracing/printk_formats 0xffffffff80713d40 : "irq_handler_entry: irq=%d handler=%s\n" 0xffffffff80713d48 : "lock_acquire: %s%s%s\n" 0xffffffff80713d50 : "lock_release: %s\n" Signed-off-by: Steven Rostedt <srostedt@redhat.com>
2009-03-12tracing/core: bring back raw trace_printk for dynamic formats stringsFrederic Weisbecker
Impact: fix callsites with dynamic format strings Since its new binary implementation, trace_printk() internally uses static containers for the format strings on each callsites. But the value is assigned once at build time, which means that it can't take dynamic formats. So this patch unearthes the raw trace_printk implementation for the callers that will need trace_printk to be able to carry these dynamic format strings. The trace_printk() macro will use the appropriate implementation for each callsite. Most of the time however, the binary implementation will still be used. The other impact of this patch is that mmiotrace_printk() will use the old implementation because it calls the low level trace_vprintk and we can't guess here whether the format passed in it is dynamic or not. Some parts of this patch have been written by Steven Rostedt (most notably the part that chooses the appropriate implementation for each callsites). Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Signed-off-by: Steven Rostedt <srostedt@redhat.com>
2009-03-06tracing/core: drop the old trace_printk() implementation in favour of ↵Frederic Weisbecker
trace_bprintk() Impact: faster and lighter tracing Now that we have trace_bprintk() which is faster and consume lesser memory than trace_printk() and has the same purpose, we can now drop the old implementation in favour of the binary one from trace_bprintk(), which means we move all the implementation of trace_bprintk() to trace_printk(), so the Api doesn't change except that we must now use trace_seq_bprintk() to print the TRACE_PRINT entries. Some changes result of this: - Previously, trace_bprintk depended of a single tracer and couldn't work without. This tracer has been dropped and the whole implementation of trace_printk() (like the module formats management) is now integrated in the tracing core (comes with CONFIG_TRACING), though we keep the file trace_printk (previously trace_bprintk.c) where we can find the module management. Thus we don't overflow trace.c - changes some parts to use trace_seq_bprintk() to print TRACE_PRINT entries. - change a bit trace_printk/trace_vprintk macros to support non-builtin formats constants, and fix 'const' qualifiers warnings. But this is all transparent for developers. - etc... V2: - Rebase against last changes - Fix mispell on the changelog V3: - Rebase against last changes (moving trace_printk() to kernel.h) Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Acked-by: Steven Rostedt <rostedt@goodmis.org> LKML-Reference: <1236356510-8381-5-git-send-email-fweisbec@gmail.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>