Messages in this thread | | | Subject | Re: [PATCH] staging: ion: fix corruption of ion_import_dma_buf | From | Shawn Lin <> | Date | Fri, 11 Sep 2015 07:51:25 +0800 |
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在 2015/9/11 0:44, Laura Abbott 写道: > On 09/09/2015 10:41 PM, Colin Cross wrote: >> On Wed, Sep 9, 2015 at 10:19 AM, Laura Abbott <labbott@redhat.com> wrote: >>> (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 >> >> I can't see any reason to not hold the mutex across ion_handle_create. >> The patch that introduced the bug >> (83271f6262c91a49df325c52bec8f00f4de294ca, ion: hold reference to >> handle after ion_uhandle_get) required that the mutex not be held >> around the call to ion_handle_put, but didn't affect >> ion_handle_create. > > Thanks for confirming. With that, >
Thanks for reviewing this patch, Laura. :)
> Reviewed-by: Laura Abbott <labbott@redhat.com> > > > >
-- Best Regards Shawn Lin
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