Messages in this thread | | | Subject | Re: [PATCH] staging: ion: fix corruption of ion_import_dma_buf | From | Laura Abbott <> | Date | Wed, 9 Sep 2015 10:19:13 -0700 |
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(adding Colin and John)
On 09/09/2015 12:41 AM, Shawn Lin wrote: > we found this issue but still exit in lastest kernel. Simply > keep ion_handle_create under mutex_lock to avoid this race. > > WARNING: CPU: 2 PID: 2648 at drivers/staging/android/ion/ion.c:512 ion_handle_add+0xb4/0xc0() > ion_handle_add: buffer already found. > Modules linked in: iwlmvm iwlwifi mac80211 cfg80211 compat > CPU: 2 PID: 2648 Comm: TimedEventQueue Tainted: G W 3.14.0 #7 > 00000000 00000000 9a3efd2c 80faf273 9a3efd6c 9a3efd5c 80935dc9 811d7fd3 > 9a3efd88 00000a58 812208a0 00000200 80e128d4 80e128d4 8d4ae00c a8cd8600 > a8cd8094 9a3efd74 80935e0e 00000009 9a3efd6c 811d7fd3 9a3efd88 9a3efd9c > Call Trace: > [<80faf273>] dump_stack+0x48/0x69 > [<80935dc9>] warn_slowpath_common+0x79/0x90 > [<80e128d4>] ? ion_handle_add+0xb4/0xc0 > [<80e128d4>] ? ion_handle_add+0xb4/0xc0 > [<80935e0e>] warn_slowpath_fmt+0x2e/0x30 > [<80e128d4>] ion_handle_add+0xb4/0xc0 > [<80e144cc>] ion_import_dma_buf+0x8c/0x110 > [<80c517c4>] reg_init+0x364/0x7d0 > [<80993363>] ? futex_wait+0x123/0x210 > [<80992e0e>] ? get_futex_key+0x16e/0x1e0 > [<8099308f>] ? futex_wake+0x5f/0x120 > [<80c51e19>] vpu_service_ioctl+0x1e9/0x500 > [<80994aec>] ? do_futex+0xec/0x8e0 > [<80971080>] ? prepare_to_wait_event+0xc0/0xc0 > [<80c51c30>] ? reg_init+0x7d0/0x7d0 > [<80a22562>] do_vfs_ioctl+0x2d2/0x4c0 > [<80b198ad>] ? inode_has_perm.isra.41+0x2d/0x40 > [<80b199cf>] ? file_has_perm+0x7f/0x90 > [<80b1a5f7>] ? selinux_file_ioctl+0x47/0xf0 > [<80a227a8>] SyS_ioctl+0x58/0x80 > [<80fb45e8>] syscall_call+0x7/0x7 > [<80fb0000>] ? mmc_do_calc_max_discard+0xab/0xe4 > > Fixes: 83271f626 ("ion: hold reference to handle...") > Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com> > --- > > drivers/staging/android/ion/ion.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/drivers/staging/android/ion/ion.c b/drivers/staging/android/ion/ion.c > index eec878e..32e7b5c 100644 > --- a/drivers/staging/android/ion/ion.c > +++ b/drivers/staging/android/ion/ion.c > @@ -1179,13 +1179,13 @@ struct ion_handle *ion_import_dma_buf(struct ion_client *client, int fd) > mutex_unlock(&client->lock); > goto end; > } > - mutex_unlock(&client->lock); > > handle = ion_handle_create(client, buffer); > - if (IS_ERR(handle)) > + if (IS_ERR(handle)) { > + mutex_unlock(&client->lock); > goto end; > + } > > - mutex_lock(&client->lock); > ret = ion_handle_add(client, handle); > mutex_unlock(&client->lock); > if (ret) { >
So the patch looks correct but the locking change there seems like it was added deliberately. Colin/John, do you remember why the locking for ion_import_dma_buf changed? Was there a deadlock condition somewhere?
Thanks, Laura
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