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ANDROID: fuse: fix deadlock for reply of FUSE_CANONICAL_PATH

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There is a deadlock when the reply of FUSE_CANONICAL_PATH from user-
space client, because the kern_path function will issue a new request
and wait the respond from client which has been in wait state. The ba-
cktrace is like this:

<6>[  518.977731] ntfs-3g         S    0  2138      1 0x04000000
<4>[  518.977745] Call trace:
<4>[  518.977757]  __switch_to+0x130/0x13c
<4>[  518.977767]  __schedule+0x740/0x964
<4>[  518.977777]  schedule+0x70/0x90
<4>[  518.977794]  __fuse_request_send+0x1a0/0x340
<4>[  518.977808]  fuse_simple_request+0x178/0x1c8
<4>[  518.977818]  fuse_lookup_name+0xfc/0x220
<4>[  518.977829]  fuse_lookup+0x48/0x134
<4>[  518.977842]  __lookup_slow+0xc8/0x154
<4>[  518.977853]  walk_component+0x1c0/0x728
<4>[  518.977863]  path_lookupat+0xa8/0x208
<4>[  518.977875]  filename_lookup+0x8c/0x190
<4>[  518.977887]  kern_path+0x30/0x3c
<4>[  518.977901]  fuse_dev_do_write+0x79c/0x114c
<4>[  518.977914]  fuse_dev_write+0x60/0x84
<4>[  518.977928]  do_iter_readv_writev+0x11c/0x158
<4>[  518.977941]  do_iter_write+0x7c/0x1b8
<4>[  518.977953]  vfs_writev+0x84/0xe8
<4>[  518.977966]  do_writev+0x78/0x114
<4>[  518.977979]  __arm64_sys_writev+0x1c/0x24
<4>[  518.977992]  el0_svc_common+0x98/0x160
<4>[  518.978005]  el0_svc_handler+0x5c/0x64
<4>[  518.978015]  el0_svc+0x8/0xc

Fixes: fa199896a3 ("ANDROID: fuse: Add support for d_canonical_path")
Signed-off-by: Cliff Chen <cliff.chen@rock-chips.com>
Change-Id: I13487e5c956c4537c2554a44208d6664653ef4f1
This commit is contained in:
Cliff Chen
2021-04-15 10:50:42 +08:00
committed by Tao Huang
parent 97a4cf0355
commit 24dace7355
1 changed files with 2 additions and 2 deletions
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4
fs/fuse/dev.c
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@@ -1913,8 +1913,8 @@ static ssize_t fuse_dev_do_write(struct fuse_dev *fud,
char *path = (char *)req->args->out_args[0].value;
path[req->args->out_args[0].size - 1] = 0;
req->out.h.error =
kern_path(path, 0, req->args->canonical_path);
if (req->out.h.error != -ENOSYS)
req->out.h.error = kern_path(path, 0, req->args->canonical_path);
}
spin_lock(&fpq->lock);