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rst: Formalize the shared resource restore order

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Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
This commit is contained in:
Pavel Emelyanov
2013-08-29 08:07:15 +04:00
parent cb648fb934
commit 7a16734ed5
4 changed files with 17 additions and 6 deletions
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7
files.c
View File

@@ -443,10 +443,9 @@ static int collect_fd(int pid, FdinfoEntry *e, struct rst_info *rst_info)
return -1; return -1;
} }
list_for_each_entry(le, &fdesc->fd_info_head, desc_list) { list_for_each_entry(le, &fdesc->fd_info_head, desc_list)
if (le->pid > new_le->pid) if (pid_rst_prio(new_le->pid, le->pid))
break; break;
}
list_add_tail(&new_le->desc_list, &le->desc_list); list_add_tail(&new_le->desc_list, &le->desc_list);
new_le->desc = fdesc; new_le->desc = fdesc;
@@ -972,7 +971,7 @@ int shared_fdt_prepare(struct pstree_item *item)
item->rst->fdt = fdt; item->rst->fdt = fdt;
item->rst->service_fd_id = fdt->nr; item->rst->service_fd_id = fdt->nr;
fdt->nr++; fdt->nr++;
if (fdt->pid > item->pid.virt) if (pid_rst_prio(item->pid.virt, fdt->pid))
fdt->pid = item->pid.virt; fdt->pid = item->pid.virt;
return 0; return 0;

10
include/crtools.h
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@@ -189,4 +189,14 @@ static inline int in_vma_area(struct vma_area *vma, unsigned long addr)
addr < (unsigned long)vma->vma.end; addr < (unsigned long)vma->vma.end;
} }
/*
* When we have to restore a shared resource, we mush select which
* task should do it, and make other(s) wait for it. In order to
* avoid deadlocks, always make task with lower pid be the restorer.
*/
static inline bool pid_rst_prio(unsigned pid_a, unsigned pid_b)
{
return pid_a < pid_b;
}
#endif /* __CR_CRTOOLS_H__ */ #endif /* __CR_CRTOOLS_H__ */

4
include/files.h
View File

@@ -6,6 +6,7 @@
#include "lock.h" #include "lock.h"
#include "list.h" #include "list.h"
#include "image.h" #include "image.h"
#include "crtools.h"
#include "protobuf/fdinfo.pb-c.h" #include "protobuf/fdinfo.pb-c.h"
#include "protobuf/fown.pb-c.h" #include "protobuf/fown.pb-c.h"
@@ -69,7 +70,8 @@ struct fdinfo_list_entry {
/* reports whether fd_a takes prio over fd_b */ /* reports whether fd_a takes prio over fd_b */
static inline int fdinfo_rst_prio(struct fdinfo_list_entry *fd_a, struct fdinfo_list_entry *fd_b) static inline int fdinfo_rst_prio(struct fdinfo_list_entry *fd_a, struct fdinfo_list_entry *fd_b)
{ {
return (fd_a->pid < fd_b->pid) || ((fd_a->pid == fd_b->pid) && (fd_a->fe->fd < fd_b->fe->fd)); return pid_rst_prio(fd_a->pid, fd_b->pid) ||
((fd_a->pid == fd_b->pid) && (fd_a->fe->fd < fd_b->fe->fd));
} }
struct file_desc_ops { struct file_desc_ops {

2
shmem.c
View File

@@ -44,7 +44,7 @@ static int collect_shmem(int pid, VmaEntry *vi)
* will wait until the kernel propagate this mapping * will wait until the kernel propagate this mapping
* into /proc * into /proc
*/ */
if (si->pid <= pid) if (!pid_rst_prio(pid, si->pid))
return 0; return 0;
si->pid = pid; si->pid = pid;