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ed463454ef
qemu/hw
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Greg Kurz ed463454ef 9p: Lock directory streams with a CoMutex 
Locking was introduced in QEMU 2.7 to address the deprecation of
readdir_r(3) in glibc 2.24. It turns out that the frontend code is
the worst place to handle a critical section with a pthread mutex:
the code runs in a coroutine on behalf of the QEMU mainloop and then
yields control, waiting for the fsdev backend to process the request
in a worker thread. If the client resends another readdir request for
the same fid before the previous one finally unlocked the mutex, we're
deadlocked.

This never bit us because the linux client serializes readdir requests
for the same fid, but it is quite easy to demonstrate with a custom
client.

A good solution could be to narrow the critical section in the worker
thread code and to return a copy of the dirent to the frontend, but
this causes quite some changes in both 9p.c and codir.c. So, instead
of that, in order for people to easily backport the fix to older QEMU
versions, let's simply use a CoMutex since all the users for this
sit in coroutines.

Fixes: 7cde47d4a8 ("9p: add locking to V9fsDir")
Reviewed-by: Christian Schoenebeck <qemu_oss@crudebyte.com>
Message-Id: <158981894794.109297.3530035833368944254.stgit@bahia.lan>
Signed-off-by: Greg Kurz <groug@kaod.org>
2020-05-25 10:38:03 +02:00
..
9pfs 9p: Lock directory streams with a CoMutex 2020-05-25 10:38:03 +02:00
acpi qdev: Unrealize must not fail 2020-05-15 07:08:14 +02:00
adc hw/*/Makefile.objs: Move many .o files to common-objs 2020-02-04 09:00:57 +01:00
alpha hw/ide: Do ide_drive_get() within pci_ide_create_devs() 2020-03-17 12:22:36 -04:00
arm hw/arm/pxa2xx: Replace hw_error() by qemu_log_mask() 2020-05-21 22:05:27 +01:00
audio qdev: Unrealize must not fail 2020-05-15 07:08:14 +02:00
block hw/block/pflash: Check return value of blk_pwrite() 2020-05-22 19:38:14 +02:00
char hw/char/xilinx_uartlite: Replace hw_error() by qemu_log_mask() 2020-05-21 22:05:27 +01:00
core various: Remove unnecessary OBJECT() cast 2020-05-15 07:08:14 +02:00
cpu qom: Drop parameter @errp of object_property_add() & friends 2020-05-15 07:07:58 +02:00
cris hw: Make MachineClass::is_default a boolean type 2020-02-28 14:57:19 -05:00
display hw/arm/pxa2xx: Replace hw_error() by qemu_log_mask() 2020-05-21 22:05:27 +01:00
dma hw/arm/pxa2xx: Replace hw_error() by qemu_log_mask() 2020-05-21 22:05:27 +01:00
gpio ARM: PL061: Introduce N_GPIOS 2020-05-21 22:05:27 +01:00
hppa hw/ide: Remove unneeded inclusion of hw/ide.h 2020-03-17 12:22:36 -04:00
hyperv qom: Drop parameter @errp of object_property_add() & friends 2020-05-15 07:07:58 +02:00
i2c hw: Remove unnecessary DEVICE() cast 2020-05-15 07:08:52 +02:00
i386 hw: Use QEMU_IS_ALIGNED() on parallel flash block size 2020-05-18 19:05:25 +02:00
ide hw/ide/ahci: Log lost IRQs 2020-05-18 19:05:25 +02:00
input qdev: Unrealize must not fail 2020-05-15 07:08:14 +02:00
intc qdev: Unrealize must not fail 2020-05-15 07:08:14 +02:00
ipack qdev: Unrealize must not fail 2020-05-15 07:08:14 +02:00
ipmi various: Remove unnecessary OBJECT() cast 2020-05-15 07:08:14 +02:00
isa Drop more @errp parameters after previous commit 2020-05-15 07:08:14 +02:00
lm32 hw: Make MachineClass::is_default a boolean type 2020-02-28 14:57:19 -05:00
m68k hw/m68k: Use memory_region_init_rom() with read-only regions 2020-03-17 15:18:47 +01:00
mem qdev: Unrealize must not fail 2020-05-15 07:08:14 +02:00
microblaze various: Remove unnecessary OBJECT() cast 2020-05-15 07:08:14 +02:00
mips smbus: Fix spd_data_generate() error API violation 2020-04-29 08:01:52 +02:00
misc hw: Move i.MX watchdog driver to hw/watchdog 2020-05-21 20:00:18 +01:00
moxie hw: Make MachineClass::is_default a boolean type 2020-02-28 14:57:19 -05:00
net hw: Remove unnecessary DEVICE() cast 2020-05-15 07:08:52 +02:00
nios2 qom: Drop parameter @errp of object_property_add() & friends 2020-05-15 07:07:58 +02:00
nubus hw: Remove unnecessary DEVICE() cast 2020-05-15 07:08:52 +02:00
nvram qdev: Unrealize must not fail 2020-05-15 07:08:14 +02:00
openrisc hw: Make MachineClass::is_default a boolean type 2020-02-28 14:57:19 -05:00
pci qdev: Unrealize must not fail 2020-05-15 07:08:14 +02:00
pci-bridge pcie_root_port: Add hotplug disabling option 2020-03-08 09:18:29 -04:00
pci-host hw: Remove unnecessary DEVICE() cast 2020-05-15 07:08:52 +02:00
pcmcia qom: Drop parameter @errp of object_property_add() & friends 2020-05-15 07:07:58 +02:00
ppc hw: Remove unnecessary DEVICE() cast 2020-05-15 07:08:52 +02:00
rdma lockable: Replace locks with lock guard macros 2020-05-04 16:07:43 +01:00
riscv hw: Use QEMU_IS_ALIGNED() on parallel flash block size 2020-05-18 19:05:25 +02:00
rtc qom: Drop parameter @errp of object_property_add() & friends 2020-05-15 07:07:58 +02:00
s390x various: Remove unnecessary OBJECT() cast 2020-05-15 07:08:14 +02:00
scsi qdev: Unrealize must not fail 2020-05-15 07:08:14 +02:00
sd qdev: Unrealize must not fail 2020-05-15 07:08:14 +02:00
semihosting semihosting: add qemu_semihosting_console_inc for SYS_READC 2020-01-09 11:41:29 +00:00
sh4 hw: Remove unnecessary DEVICE() cast 2020-05-15 07:08:52 +02:00
smbios hw/smbios/smbios: Remove unused include 2020-02-06 10:38:57 +01:00
sparc qom: Drop parameter @errp of object_property_add() & friends 2020-05-15 07:07:58 +02:00
sparc64 qom: Drop parameter @errp of object_property_add() & friends 2020-05-15 07:07:58 +02:00
ssi qom: Drop parameter @errp of object_property_add() & friends 2020-05-15 07:07:58 +02:00
timer hw/timer/exynos4210_mct: Replace hw_error() by qemu_log_mask() 2020-05-21 22:05:27 +01:00
tpm hw/tpm: fix usage of bool in tpm-tis.c 2020-05-12 11:47:24 -04:00
tricore hw: Do not initialize MachineClass::is_default to 0 2020-02-28 14:57:19 -05:00
unicore32 hw: Make MachineClass::is_default a boolean type 2020-02-28 14:57:19 -05:00
usb qdev: Unrealize must not fail 2020-05-15 07:08:14 +02:00
vfio Revert "hw/display/ramfb: initialize fw-config space with xres/ yres" 2020-05-18 15:42:34 +02:00
virtio qdev: Unrealize must not fail 2020-05-15 07:08:14 +02:00
watchdog hw/watchdog: Implement full i.MX watchdog support 2020-05-21 20:00:18 +01:00
xen hw: Remove unnecessary DEVICE() cast 2020-05-15 07:08:52 +02:00
xenpv trivial: Remove xenfb_enabled from sysemu.h 2020-02-04 09:00:57 +01:00
xtensa hw/xtensa/xtfpga:fix leak of fdevice tree blob 2020-02-19 10:33:38 +01:00
Kconfig Remove the core bluetooth code 2019-12-17 09:01:14 +01:00
Makefile.objs Remove the core bluetooth code 2019-12-17 09:01:14 +01:00