CVS log for src/sys/kern/subr_pcu.c

Up to [cvs.NetBSD.org] / src / sys / kern

Request diff between arbitrary revisions

Default branch: MAIN
Current tag: phil-wifi-20191119

Revision 1.21 / (download) - annotate - [select for diffs], Mon Oct 16 15:03:57 2017 UTC (6 years, 6 months ago) by bouyer
Branch: MAIN
CVS Tags: tls-maxphys-base-20171202, phil-wifi-base, phil-wifi-20200421, phil-wifi-20200411, phil-wifi-20200406, phil-wifi-20191119, phil-wifi-20190609, phil-wifi, pgoyette-compat-merge-20190127, pgoyette-compat-base, pgoyette-compat-20190127, pgoyette-compat-20190118, pgoyette-compat-1226, pgoyette-compat-1126, pgoyette-compat-1020, pgoyette-compat-0930, pgoyette-compat-0906, pgoyette-compat-0728, pgoyette-compat-0625, pgoyette-compat-0521, pgoyette-compat-0502, pgoyette-compat-0422, pgoyette-compat-0415, pgoyette-compat-0407, pgoyette-compat-0330, pgoyette-compat-0322, pgoyette-compat-0315, pgoyette-compat, netbsd-9-base, netbsd-9-0-RELEASE, netbsd-9-0-RC2, netbsd-9-0-RC1, isaki-audio2-base, isaki-audio2, is-mlppp-base, is-mlppp, bouyer-xenpvh-base2, bouyer-xenpvh-base1, bouyer-xenpvh-base, bouyer-xenpvh, ad-namecache-base3, ad-namecache-base2, ad-namecache-base1, ad-namecache-base, ad-namecache
Branch point for: netbsd-9
Changes since 1.20: +4 -3 lines
Diff to previous 1.20 (colored)

PR port-arm/52603:
There is a race here, as seen on arm with FPU:
LWP L is running but not on CPU, has its FPU state on CPU2 which
has not been released yet, so fpexc still has VFP_FPEXC_EN set in the PCB copy.

LWP L is scheduled on CPU1, CPU1 calls cpu_switchto() for L in mi_switch().
cpu_switchto() will set VFP_FPEXC_EN in the FPU's fpexc register per the
PCB fpexc copy.

Before CPU1 calls pcu_switchpoint() for L, CPU2 calls
pcu_do_op(PCU_CMD_SAVE | PCU_CMD_RELEASE) for L because it still holds its
FPU state and wants to load another lwp. This cause VFP_FPEXC_EN to
be cleared in the PCB copy, but not in CPU1's register. L's l_pcu_cpu is
set to NULL.

When CPU1 calls pcu_switchpoint() for L it see l_pcu_cpu is NULL, and doesn't
call the release callback.

Now CPU1 has its FPU enabled but with the wrong FPU state.

Fix by releasing the PCU even if l_pcu_cpu is NULL.

This form allows you to request diff's between any two revisions of a file. You may select a symbolic revision name using the selection box or you may type in a numeric name using the type-in text box.