mirror of https://github.com/torvalds/linux.git
a9f70bd4e7
The first is something that has come up a few times and has been worked out individually, but it's come up now enough that the problem should be generic. Tracepoints are protected by RCU sched. There are several tracepoints within core infrastructure like kfree(). If a tracepoint is called when the CPU is going down, or when it's coming up but has yet to be recognized by RCU, a RCU warning is triggered. This is a true bug as that tracepoint is not protected by RCU. Usually, this is taken care of by testing for cpu online as a tracepoint condition. But as this is happening more often, moving it from a individual tracepoint to a check in the tracepoint infrastructure is more robust. Note, there is now a duplicate of a cpu online test, because this update does not remove the individual checks. But the overhead is small enough that the removal can be done in another release. The second change is strange linker breakage due to the branch tracer's builtin_constant_p() check failing, and treating the condition as a variable instead of a constant. Arnd Bergmann found that this can be fixed by testing !!(cond) instead of just (cond). -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQEcBAABAgAGBQJWw2vTAAoJEKKk/i67LK/8vkMIAI+Fx+S9sCeWVGp4VZ3DKH9K DibRD/2KREZe1AjYEU8ZAgo+VsFzW8OHiI1TI/1jP61YkiQSIhu6kVdPCoLG5buy 8WwiKEQ94VWC1hbPOiiq3K7THEu+M8zuFdU3+odS8E3sXIGqKPKQ3iFwwfTVHI6o /cMTuefqsxo/hj8VwwaZdwlgWwLltM8sR040auTTEsqBLZ7D1q0aCyBrnju3FtBt uSIPK91d92ANkpq3ELDihxBa41XSEahYgGm/ozewjHwpooWvIQz4tpGaxxkyltuE RzeYBrM5LNBQUaXZ6C6jAdL0Y+bukS2MdNUjv8U6LwKbUvQoLuYteGEQ9g/m+mE= =8LDX -----END PGP SIGNATURE----- Merge tag 'trace-fixes-v4.5-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace Pull tracing fixes from Steven Rostedt: "This includes two fixes. The first is something that has come up a few times and has been worked out individually, but it's come up now enough that the problem should be generic. Tracepoints are protected by RCU sched. There are several tracepoints within core infrastructure like kfree(). If a tracepoint is called when the CPU is going down, or when it's coming up but has yet to be recognized by RCU, a RCU warning is triggered. This is a true bug as that tracepoint is not protected by RCU. Usually, this is taken care of by testing for cpu online as a tracepoint condition. But as this is happening more often, moving it from a individual tracepoint to a check in the tracepoint infrastructure is more robust. Note, there is now a duplicate of a cpu online test, because this update does not remove the individual checks. But the overhead is small enough that the removal can be done in another release. The second change is strange linker breakage due to the branch tracer's builtin_constant_p() check failing, and treating the condition as a variable instead of a constant. Arnd Bergmann found that this can be fixed by testing !!(cond) instead of just (cond)" * tag 'trace-fixes-v4.5-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: tracing: Fix freak link error caused by branch tracer tracepoints: Do not trace when cpu is offline |
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