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o Lock accesses to the page queues.

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o Add a comment explaining why hoisting the page queue lock outside
   of a particular loop is not possible.
This commit is contained in:
Alan Cox 2002-07-13 04:09:45 +00:00
parent 03d7a9fffb
commit b416fa1041
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=99899
1 changed files with 11 additions and 0 deletions
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11
sys/kern/sys_pipe.c
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@ -616,18 +616,27 @@ pipe_build_write_buffer(wpipe, uio)
for (i = 0; addr < endaddr; addr += PAGE_SIZE, i++) {
vm_page_t m;
/*
* vm_fault_quick() can sleep. Consequently,
* vm_page_lock_queue() and vm_page_unlock_queue()
* should not be performed outside of this loop.
*/
if (vm_fault_quick((caddr_t)addr, VM_PROT_READ) < 0 ||
(paddr = pmap_extract(vmspace_pmap(curproc->p_vmspace),
addr)) == 0) {
int j;
vm_page_lock_queues();
for (j = 0; j < i; j++)
vm_page_unwire(wpipe->pipe_map.ms[j], 1);
vm_page_unlock_queues();
return (EFAULT);
}
m = PHYS_TO_VM_PAGE(paddr);
vm_page_lock_queues();
vm_page_wire(m);
vm_page_unlock_queues();
wpipe->pipe_map.ms[i] = m;
}
@ -690,8 +699,10 @@ pipe_destroy_write_buffer(wpipe)
amountpipekva -= wpipe->pipe_buffer.size + PAGE_SIZE;
}
}
vm_page_lock_queues();
for (i = 0; i < wpipe->pipe_map.npages; i++)
vm_page_unwire(wpipe->pipe_map.ms[i], 1);
vm_page_unlock_queues();
wpipe->pipe_map.npages = 0;
}