block: Prevent coroutine stack overflow when recursing in bdrv_open_backing_file.

In 1.7.1 qcow2_create2 reopen the file for flushing without the BDRV_O_NO_BACKING
flags.

As a consequence the code would recursively open the whole backing chain.

These three stack arrays would pile up through the recursion and lead to a coroutine
stack overflow.

Convert these array to malloced buffers in order to streamline the coroutine
footprint.

Symptoms where freezes or segfaults on production machines while taking QMP externals
snapshots. The overflow disturbed coroutine switching.

[Resolved conflicts on qemu.git/master since the patch was against v1.7.1
--Stefan]

Signed-off-by: Benoit Canet <benoit.canet@gmail.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
1 file changed
tree: 32c70dc0d83f4d06f4a2aae861557e73fd04ef77
  1. audio/
  2. backends/
  3. block/
  4. bsd-user/
  5. default-configs/
  6. disas/
  7. docs/
  8. fpu/
  9. fsdev/
  10. gdb-xml/
  11. hw/
  12. include/
  13. libcacard/
  14. linux-headers/
  15. linux-user/
  16. net/
  17. pc-bios/
  18. po/
  19. qapi/
  20. qga/
  21. qobject/
  22. qom/
  23. roms/
  24. scripts/
  25. slirp/
  26. stubs/
  27. sysconfigs/
  28. target-alpha/
  29. target-arm/
  30. target-cris/
  31. target-i386/
  32. target-lm32/
  33. target-m68k/
  34. target-microblaze/
  35. target-mips/
  36. target-moxie/
  37. target-openrisc/
  38. target-ppc/
  39. target-s390x/
  40. target-sh4/
  41. target-sparc/
  42. target-unicore32/
  43. target-xtensa/
  44. tcg/
  45. tests/
  46. trace/
  47. ui/
  48. util/
  49. .exrc
  50. .gitignore
  51. .gitmodules
  52. .mailmap
  53. .travis.yml
  54. aio-posix.c
  55. aio-win32.c
  56. arch_init.c
  57. async.c
  58. balloon.c
  59. block-migration.c
  60. block.c
  61. blockdev-nbd.c
  62. blockdev.c
  63. blockjob.c
  64. bt-host.c
  65. bt-vhci.c
  66. Changelog
  67. CODING_STYLE
  68. configure
  69. COPYING
  70. COPYING.LIB
  71. coroutine-gthread.c
  72. coroutine-sigaltstack.c
  73. coroutine-ucontext.c
  74. coroutine-win32.c
  75. cpu-exec.c
  76. cpus.c
  77. cputlb.c
  78. device-hotplug.c
  79. device_tree.c
  80. disas.c
  81. dma-helpers.c
  82. dump.c
  83. exec.c
  84. gdbstub.c
  85. HACKING
  86. hmp-commands.hx
  87. hmp.c
  88. hmp.h
  89. iohandler.c
  90. ioport.c
  91. iothread.c
  92. kvm-all.c
  93. kvm-stub.c
  94. LICENSE
  95. main-loop.c
  96. MAINTAINERS
  97. Makefile
  98. Makefile.objs
  99. Makefile.target
  100. memory.c
  101. memory_mapping.c
  102. migration-exec.c
  103. migration-fd.c
  104. migration-rdma.c
  105. migration-tcp.c
  106. migration-unix.c
  107. migration.c
  108. module-common.c
  109. monitor.c
  110. nbd.c
  111. os-posix.c
  112. os-win32.c
  113. page_cache.c
  114. qapi-schema.json
  115. qdev-monitor.c
  116. qdict-test-data.txt
  117. qemu-bridge-helper.c
  118. qemu-char.c
  119. qemu-coroutine-io.c
  120. qemu-coroutine-lock.c
  121. qemu-coroutine-sleep.c
  122. qemu-coroutine.c
  123. qemu-doc.texi
  124. qemu-file.c
  125. qemu-img-cmds.hx
  126. qemu-img.c
  127. qemu-img.texi
  128. qemu-io-cmds.c
  129. qemu-io.c
  130. qemu-log.c
  131. qemu-nbd.c
  132. qemu-nbd.texi
  133. qemu-options-wrapper.h
  134. qemu-options.h
  135. qemu-options.hx
  136. qemu-seccomp.c
  137. qemu-tech.texi
  138. qemu-timer.c
  139. qemu.nsi
  140. qemu.sasl
  141. qmp-commands.hx
  142. qmp.c
  143. qtest.c
  144. README
  145. rules.mak
  146. savevm.c
  147. spice-qemu-char.c
  148. tcg-runtime.c
  149. tci.c
  150. thread-pool.c
  151. thunk.c
  152. tpm.c
  153. trace-events
  154. translate-all.c
  155. translate-all.h
  156. user-exec.c
  157. VERSION
  158. version.rc
  159. vl.c
  160. vmstate.c
  161. xbzrle.c
  162. xen-all.c
  163. xen-mapcache.c
  164. xen-stub.c