Author: jah Date: Sat Jan 21 06:48:52 2017 New Revision: 312561 URL: https://svnweb.freebsd.org/changeset/base/312561
Log: MFC r312153, r312191 r312153: For i386 temporary mappings, unpin the thread before releasing the cmap lock. Releasing the lock first may result in the thread being immediately rescheduled and bound to the same CPU, only to unpin itself upon resuming execution. Noted by: skra (in review for armv6 equivalent) r312191: Add comment explaining relative order of sched_unpin() and mtx_unlock(). Suggested by: alc Modified: stable/11/sys/i386/i386/pmap.c Directory Properties: stable/11/ (props changed) Modified: stable/11/sys/i386/i386/pmap.c ============================================================================== --- stable/11/sys/i386/i386/pmap.c Fri Jan 20 22:41:16 2017 (r312560) +++ stable/11/sys/i386/i386/pmap.c Sat Jan 21 06:48:52 2017 (r312561) @@ -4231,8 +4231,14 @@ pmap_zero_page(vm_page_t m) invlcaddr(pc->pc_cmap_addr2); pagezero(pc->pc_cmap_addr2); *cmap_pte2 = 0; - mtx_unlock(&pc->pc_cmap_lock); + + /* + * Unpin the thread before releasing the lock. Otherwise the thread + * could be rescheduled while still bound to the current CPU, only + * to unpin itself immediately upon resuming execution. + */ sched_unpin(); + mtx_unlock(&pc->pc_cmap_lock); } /* @@ -4261,8 +4267,8 @@ pmap_zero_page_area(vm_page_t m, int off else bzero(pc->pc_cmap_addr2 + off, size); *cmap_pte2 = 0; - mtx_unlock(&pc->pc_cmap_lock); sched_unpin(); + mtx_unlock(&pc->pc_cmap_lock); } /* @@ -4316,8 +4322,8 @@ pmap_copy_page(vm_page_t src, vm_page_t bcopy(pc->pc_cmap_addr1, pc->pc_cmap_addr2, PAGE_SIZE); *cmap_pte1 = 0; *cmap_pte2 = 0; - mtx_unlock(&pc->pc_cmap_lock); sched_unpin(); + mtx_unlock(&pc->pc_cmap_lock); } int unmapped_buf_allowed = 1; @@ -4364,8 +4370,8 @@ pmap_copy_pages(vm_page_t ma[], vm_offse } *cmap_pte1 = 0; *cmap_pte2 = 0; - mtx_unlock(&pc->pc_cmap_lock); sched_unpin(); + mtx_unlock(&pc->pc_cmap_lock); } /* @@ -5349,8 +5355,8 @@ pmap_flush_page(vm_page_t m) if (useclflushopt || cpu_vendor_id != CPU_VENDOR_INTEL) mfence(); *cmap_pte2 = 0; - mtx_unlock(&pc->pc_cmap_lock); sched_unpin(); + mtx_unlock(&pc->pc_cmap_lock); } else pmap_invalidate_cache(); } _______________________________________________ svn-src-all@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"