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258541 |
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25-Nov-2013 |
attilio |
- For kernel compiled only with KDTRACE_HOOKS and not any lock debugging option, unbreak the lock tracing release semantic by embedding calls to LOCKSTAT_PROFILE_RELEASE_LOCK() direclty in the inlined version of the releasing functions for mutex, rwlock and sxlock. Failing to do so skips the lockstat_probe_func invokation for unlocking. - As part of the LOCKSTAT support is inlined in mutex operation, for kernel compiled without lock debugging options, potentially every consumer must be compiled including opt_kdtrace.h. Fix this by moving KDTRACE_HOOKS into opt_global.h and remove the dependency by opt_kdtrace.h for all files, as now only KDTRACE_FRAMES is linked there and it is only used as a compile-time stub [0].
[0] immediately shows some new bug as DTRACE-derived support for debug in sfxge is broken and it was never really tested. As it was not including correctly opt_kdtrace.h before it was never enabled so it was kept broken for a while. Fix this by using a protection stub, leaving sfxge driver authors the responsibility for fixing it appropriately [1].
Sponsored by: EMC / Isilon storage division Discussed with: rstone [0] Reported by: rstone [1] Discussed with: philip
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254268 |
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13-Aug-2013 |
markj |
FreeBSD's DTrace implementation has a few problems with respect to handling probes declared in a kernel module when that module is unloaded. In particular,
* Unloading a module with active SDT probes will cause a panic. [1] * A module's (FBT/SDT) probes aren't destroyed when the module is unloaded; trying to use them after the fact will generally cause a panic.
This change fixes both problems by porting the DTrace module load/unload handlers from illumos and registering them with the corresponding EVENTHANDLER(9) handlers. This allows the DTrace framework to destroy all probes defined in a module when that module is unloaded, and to prevent a module unload from proceeding if some of its probes are active. The latter problem has already been fixed for FBT probes by checking lf->nenabled in kern_kldunload(), but moving the check into the DTrace framework generalizes it to all kernel providers and also fixes a race in the current implementation (since a probe may be activated between the check and the call to linker_file_unload()).
Additionally, the SDT implementation has been reworked to define SDT providers/probes/argtypes in linker sets rather than using SYSINIT/SYSUNINIT to create and destroy SDT probes when a module is loaded or unloaded. This simplifies things quite a bit since it means that pretty much all of the SDT code can live in sdt.ko, and since it becomes easier to integrate SDT with the DTrace framework. Furthermore, this allows FreeBSD to be quite flexible in that SDT providers spanning multiple modules can be created on the fly when a module is loaded; at the moment it looks like illumos' SDT implementation requires all SDT probes to be statically defined in a single kernel table.
PR: 166927, 166926, 166928 Reported by: davide [1] Reviewed by: avg, trociny (earlier version) MFC after: 1 month
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233552 |
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27-Mar-2012 |
rstone |
Instead of only iterating over the set of known SDT probes when sdt.ko is loaded and unloaded, also have sdt.ko register callbacks with kern_sdt.c that will be called when a newly loaded KLD module adds more probes or a module with probes is unloaded.
This fixes two issues: first, if a module with SDT probes was loaded after sdt.ko was loaded, those new probes would not be available in DTrace. Second, if a module with SDT probes was unloaded while sdt.ko was loaded, the kernel would panic the next time DTrace had cause to try and do anything with the no-longer-existent probes.
This makes it possible to create SDT probes in KLD modules, although there are still two caveats: first, any SDT probes in a KLD module must be part of a DTrace provider that is defined in that module. At present DTrace only destroys probes when the provider is destroyed, so you can still panic the system if a KLD module creates new probes in a provider from a different module(including the kernel) and then unload the the first module.
Second, the system will panic if you unload a module containing SDT probes while there is an active D script that has enabled those probes.
MFC after: 1 month
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179089 |
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18-May-2008 |
jb |
Add kernel support for the Statically Defined Trace provider.
This is BSD licensed code written specifically for FreeBSD.
It initialises using SYSINIT so that the SDT provider, probe and argument description linkage is done whenever a module is loaded, regardless of whether the DTrace modules are loaded or not.
This file is optionally compiled into the kernel if the KDTRACE_HOOKS option is defined.
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