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<div class="moz-cite-prefix">Yeah, that should work.<br>
<br>
Christian.<br>
<br>
Am 22.03.19 um 08:34 schrieb zhoucm1:<br>
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<p>how about the attached?</p>
<p>If ok, I will merge to pathc#1.</p>
<p><br>
</p>
<p>-David<br>
</p>
<br>
<div class="moz-cite-prefix">On 2019年03月21日 22:40, Christian König
wrote:<br>
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<div class="moz-cite-prefix">No, atomic cmpxchg is a hardware
operation. If you want to replace that you need a lock again.<br>
<br>
Maybe just add a comment and use an explicit cast to void* ?
Not sure if that silences the warning.<br>
<br>
Christian.<br>
<br>
Am 21.03.19 um 15:13 schrieb Zhou, David(ChunMing):<br>
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<div>cmpxchg be replaced by some simple c sentance?<br>
otherwise we have to remove __rcu of chian->prev.<br>
<br>
-David<br>
<br>
-------- Original Message --------<br>
Subject: Re: [PATCH 1/9] dma-buf: add new dma_fence_chain
container v6<br>
From: Christian König <br>
To: "Zhou, David(ChunMing)" ,kbuild test robot ,"Zhou,
David(ChunMing)" <br>
CC: <a class="moz-txt-link-abbreviated"
href="mailto:kbuild-all@01.org,dri-devel@lists.freedesktop.org,amd-gfx@lists.freedesktop.org,lionel.g.landwerlin@intel.com,jason@jlekstrand.net"
moz-do-not-send="true">kbuild-all@01.org,dri-devel@lists.freedesktop.org,amd-gfx@lists.freedesktop.org,lionel.g.landwerlin@intel.com,jason@jlekstrand.net</a>,"Koenig,
Christian" ,"Hector, Tobias" <br>
<br>
</div>
<font size="2"><span style="font-size:11pt;">
<div class="PlainText">Hi David,<br>
<br>
For the cmpxchg() case I of hand don't know either.
Looks like so far <br>
nobody has used cmpxchg() with rcu protected structures.<br>
<br>
The other cases should be replaced by RCU_INIT_POINTER()
or <br>
rcu_dereference_protected(.., true);<br>
<br>
Regards,<br>
Christian.<br>
<br>
Am 21.03.19 um 07:34 schrieb zhoucm1:<br>
> Hi Lionel and Christian,<br>
><br>
> Below is robot report for chain->prev, which was
added __rcu as you <br>
> suggested.<br>
><br>
> How to fix this line "tmp =
cmpxchg(&chain->prev, prev, replacement); "?<br>
> I checked kernel header file, seems it has no
cmpxchg for rcu.<br>
><br>
> Any suggestion to fix this robot report?<br>
><br>
> Thanks,<br>
> -David<br>
><br>
> On 2019年03月21日 08:24, kbuild test robot wrote:<br>
>> Hi Chunming,<br>
>><br>
>> I love your patch! Perhaps something to
improve:<br>
>><br>
>> [auto build test WARNING on linus/master]<br>
>> [also build test WARNING on v5.1-rc1
next-20190320]<br>
>> [if your patch is applied to the wrong git
tree, please drop us a <br>
>> note to help improve the system]<br>
>><br>
>> url: <br>
>> <a
href="https://github.com/0day-ci/linux/commits/Chunming-Zhou/dma-buf-add-new-dma_fence_chain-container-v6/20190320-223607"
moz-do-not-send="true">
https://github.com/0day-ci/linux/commits/Chunming-Zhou/dma-buf-add-new-dma_fence_chain-container-v6/20190320-223607</a><br>
>> reproduce:<br>
>> # apt-get install sparse<br>
>> make ARCH=x86_64 allmodconfig<br>
>> make C=1 CF='-fdiagnostic-prefix
-D__CHECK_ENDIAN__'<br>
>><br>
>><br>
>> sparse warnings: (new ones prefixed by
>>)<br>
>><br>
>>>>
drivers/dma-buf/dma-fence-chain.c:73:23: sparse:
incorrect type in <br>
>>>> initializer (different address spaces)
@@ expected struct <br>
>>>> dma_fence [noderef] <asn:4>*__old
@@ got dma_fence [noderef] <br>
>>>> <asn:4>*__old @@<br>
>> drivers/dma-buf/dma-fence-chain.c:73:23:
expected struct <br>
>> dma_fence [noderef] <asn:4>*__old<br>
>> drivers/dma-buf/dma-fence-chain.c:73:23:
got struct dma_fence <br>
>> *[assigned] prev<br>
>>>>
drivers/dma-buf/dma-fence-chain.c:73:23: sparse:
incorrect type in <br>
>>>> initializer (different address spaces)
@@ expected struct <br>
>>>> dma_fence [noderef] <asn:4>*__new
@@ got dma_fence [noderef] <br>
>>>> <asn:4>*__new @@<br>
>> drivers/dma-buf/dma-fence-chain.c:73:23:
expected struct <br>
>> dma_fence [noderef] <asn:4>*__new<br>
>> drivers/dma-buf/dma-fence-chain.c:73:23:
got struct dma_fence <br>
>> *[assigned] replacement<br>
>>>>
drivers/dma-buf/dma-fence-chain.c:73:21: sparse:
incorrect type in <br>
>>>> assignment (different address spaces)
@@ expected struct <br>
>>>> dma_fence *tmp @@ got struct
dma_fence [noderef] <struct <br>
>>>> dma_fence *tmp @@<br>
>> drivers/dma-buf/dma-fence-chain.c:73:21:
expected struct <br>
>> dma_fence *tmp<br>
>> drivers/dma-buf/dma-fence-chain.c:73:21:
got struct dma_fence <br>
>> [noderef] <asn:4>*[assigned] __ret<br>
>>>>
drivers/dma-buf/dma-fence-chain.c:190:28: sparse:
incorrect type in <br>
>>>> argument 1 (different address spaces)
@@ expected struct <br>
>>>> dma_fence *fence @@ got struct
dma_fence struct dma_fence *fence @@<br>
>>
drivers/dma-buf/dma-fence-chain.c:190:28: expected
struct <br>
>> dma_fence *fence<br>
>>
drivers/dma-buf/dma-fence-chain.c:190:28: got struct
dma_fence <br>
>> [noderef] <asn:4>*prev<br>
>>>>
drivers/dma-buf/dma-fence-chain.c:222:21: sparse:
incorrect type in <br>
>>>> assignment (different address spaces)
@@ expected struct <br>
>>>> dma_fence [noderef] <asn:4>*prev
@@ got [noderef] <asn:4>*prev @@<br>
>>
drivers/dma-buf/dma-fence-chain.c:222:21: expected
struct <br>
>> dma_fence [noderef] <asn:4>*prev<br>
>>
drivers/dma-buf/dma-fence-chain.c:222:21: got struct
dma_fence <br>
>> *prev<br>
>> drivers/dma-buf/dma-fence-chain.c:235:33:
sparse: expression <br>
>> using sizeof(void)<br>
>> drivers/dma-buf/dma-fence-chain.c:235:33:
sparse: expression <br>
>> using sizeof(void)<br>
>><br>
>> vim +73 drivers/dma-buf/dma-fence-chain.c<br>
>><br>
>> 38<br>
>> 39 /**<br>
>> 40 * dma_fence_chain_walk - chain
walking function<br>
>> 41 * @fence: current chain node<br>
>> 42 *<br>
>> 43 * Walk the chain to the next node.
Returns the next fence <br>
>> or NULL if we are at<br>
>> 44 * the end of the chain. Garbage
collects chain nodes <br>
>> which are already<br>
>> 45 * signaled.<br>
>> 46 */<br>
>> 47 struct dma_fence
*dma_fence_chain_walk(struct dma_fence <br>
>> *fence)<br>
>> 48 {<br>
>> 49 struct dma_fence_chain *chain,
*prev_chain;<br>
>> 50 struct dma_fence *prev,
*replacement, *tmp;<br>
>> 51<br>
>> 52 chain =
to_dma_fence_chain(fence);<br>
>> 53 if (!chain) {<br>
>> 54 dma_fence_put(fence);<br>
>> 55 return NULL;<br>
>> 56 }<br>
>> 57<br>
>> 58 while ((prev =
dma_fence_chain_get_prev(chain))) {<br>
>> 59<br>
>> 60 prev_chain =
to_dma_fence_chain(prev);<br>
>> 61 if (prev_chain) {<br>
>> 62 if
(!dma_fence_is_signaled(prev_chain->fence))<br>
>> 63 break;<br>
>> 64<br>
>> 65 replacement = <br>
>> dma_fence_chain_get_prev(prev_chain);<br>
>> 66 } else {<br>
>> 67 if
(!dma_fence_is_signaled(prev))<br>
>> 68 break;<br>
>> 69<br>
>> 70 replacement = NULL;<br>
>> 71 }<br>
>> 72<br>
>> > 73 tmp =
cmpxchg(&chain->prev, prev, replacement);<br>
>> 74 if (tmp == prev)<br>
>> 75 dma_fence_put(tmp);<br>
>> 76 else<br>
>> 77
dma_fence_put(replacement);<br>
>> 78 dma_fence_put(prev);<br>
>> 79 }<br>
>> 80<br>
>> 81 dma_fence_put(fence);<br>
>> 82 return prev;<br>
>> 83 }<br>
>> 84 EXPORT_SYMBOL(dma_fence_chain_walk);<br>
>> 85<br>
>> 86 /**<br>
>> 87 * dma_fence_chain_find_seqno - find
fence chain node by <br>
>> seqno<br>
>> 88 * @pfence: pointer to the chain
node where to start<br>
>> 89 * @seqno: the sequence number to
search for<br>
>> 90 *<br>
>> 91 * Advance the fence pointer to the
chain node which will <br>
>> signal this sequence<br>
>> 92 * number. If no sequence number is
provided then this is <br>
>> a no-op.<br>
>> 93 *<br>
>> 94 * Returns EINVAL if the fence is
not a chain node or the <br>
>> sequence number has<br>
>> 95 * not yet advanced far enough.<br>
>> 96 */<br>
>> 97 int
dma_fence_chain_find_seqno(struct dma_fence **pfence, <br>
>> uint64_t seqno)<br>
>> 98 {<br>
>> 99 struct dma_fence_chain *chain;<br>
>> 100<br>
>> 101 if (!seqno)<br>
>> 102 return 0;<br>
>> 103<br>
>> 104 chain =
to_dma_fence_chain(*pfence);<br>
>> 105 if (!chain ||
chain->base.seqno < seqno)<br>
>> 106 return -EINVAL;<br>
>> 107<br>
>> 108
dma_fence_chain_for_each(*pfence, &chain->base) {<br>
>> 109 if ((*pfence)->context !=
chain->base.context ||<br>
>> 110
to_dma_fence_chain(*pfence)->prev_seqno < seqno)<br>
>> 111 break;<br>
>> 112 }<br>
>> 113
dma_fence_put(&chain->base);<br>
>> 114<br>
>> 115 return 0;<br>
>> 116 }<br>
>> 117
EXPORT_SYMBOL(dma_fence_chain_find_seqno);<br>
>> 118<br>
>> 119 static const char
*dma_fence_chain_get_driver_name(struct <br>
>> dma_fence *fence)<br>
>> 120 {<br>
>> 121 return "dma_fence_chain";<br>
>> 122 }<br>
>> 123<br>
>> 124 static const char <br>
>> *dma_fence_chain_get_timeline_name(struct
dma_fence *fence)<br>
>> 125 {<br>
>> 126 return "unbound";<br>
>> 127 }<br>
>> 128<br>
>> 129 static void
dma_fence_chain_irq_work(struct irq_work *work)<br>
>> 130 {<br>
>> 131 struct dma_fence_chain *chain;<br>
>> 132<br>
>> 133 chain = container_of(work,
typeof(*chain), work);<br>
>> 134<br>
>> 135 /* Try to rearm the callback */<br>
>> 136 if
(!dma_fence_chain_enable_signaling(&chain->base))<br>
>> 137 /* Ok, we are done. No more
unsignaled fences left */<br>
>> 138
dma_fence_signal(&chain->base);<br>
>> 139
dma_fence_put(&chain->base);<br>
>> 140 }<br>
>> 141<br>
>> 142 static void
dma_fence_chain_cb(struct dma_fence *f, struct <br>
>> dma_fence_cb *cb)<br>
>> 143 {<br>
>> 144 struct dma_fence_chain *chain;<br>
>> 145<br>
>> 146 chain = container_of(cb,
typeof(*chain), cb);<br>
>> 147
irq_work_queue(&chain->work);<br>
>> 148 dma_fence_put(f);<br>
>> 149 }<br>
>> 150<br>
>> 151 static bool
dma_fence_chain_enable_signaling(struct <br>
>> dma_fence *fence)<br>
>> 152 {<br>
>> 153 struct dma_fence_chain *head =
to_dma_fence_chain(fence);<br>
>> 154<br>
>> 155
dma_fence_get(&head->base);<br>
>> 156 dma_fence_chain_for_each(fence,
&head->base) {<br>
>> 157 struct dma_fence_chain
*chain = <br>
>> to_dma_fence_chain(fence);<br>
>> 158 struct dma_fence *f = chain
? chain->fence : fence;<br>
>> 159<br>
>> 160 dma_fence_get(f);<br>
>> 161 if
(!dma_fence_add_callback(f, &head->cb, <br>
>> dma_fence_chain_cb)) {<br>
>> 162 dma_fence_put(fence);<br>
>> 163 return true;<br>
>> 164 }<br>
>> 165 dma_fence_put(f);<br>
>> 166 }<br>
>> 167
dma_fence_put(&head->base);<br>
>> 168 return false;<br>
>> 169 }<br>
>> 170<br>
>> 171 static bool
dma_fence_chain_signaled(struct dma_fence *fence)<br>
>> 172 {<br>
>> 173 dma_fence_chain_for_each(fence,
fence) {<br>
>> 174 struct dma_fence_chain
*chain = <br>
>> to_dma_fence_chain(fence);<br>
>> 175 struct dma_fence *f = chain
? chain->fence : fence;<br>
>> 176<br>
>> 177 if
(!dma_fence_is_signaled(f)) {<br>
>> 178 dma_fence_put(fence);<br>
>> 179 return false;<br>
>> 180 }<br>
>> 181 }<br>
>> 182<br>
>> 183 return true;<br>
>> 184 }<br>
>> 185<br>
>> 186 static void
dma_fence_chain_release(struct dma_fence *fence)<br>
>> 187 {<br>
>> 188 struct dma_fence_chain *chain =
<br>
>> to_dma_fence_chain(fence);<br>
>> 189<br>
>> > 190
dma_fence_put(chain->prev);<br>
>> 191 dma_fence_put(chain->fence);<br>
>> 192 dma_fence_free(fence);<br>
>> 193 }<br>
>> 194<br>
>> 195 const struct dma_fence_ops
dma_fence_chain_ops = {<br>
>> 196 .get_driver_name =
dma_fence_chain_get_driver_name,<br>
>> 197 .get_timeline_name =
dma_fence_chain_get_timeline_name,<br>
>> 198 .enable_signaling =
dma_fence_chain_enable_signaling,<br>
>> 199 .signaled =
dma_fence_chain_signaled,<br>
>> 200 .release =
dma_fence_chain_release,<br>
>> 201 };<br>
>> 202 EXPORT_SYMBOL(dma_fence_chain_ops);<br>
>> 203<br>
>> 204 /**<br>
>> 205 * dma_fence_chain_init - initialize
a fence chain<br>
>> 206 * @chain: the chain node to
initialize<br>
>> 207 * @prev: the previous fence<br>
>> 208 * @fence: the current fence<br>
>> 209 *<br>
>> 210 * Initialize a new chain node and
either start a new <br>
>> chain or add the node to<br>
>> 211 * the existing chain of the
previous fence.<br>
>> 212 */<br>
>> 213 void dma_fence_chain_init(struct
dma_fence_chain *chain,<br>
>> 214 struct dma_fence
*prev,<br>
>> 215 struct dma_fence
*fence,<br>
>> 216 uint64_t seqno)<br>
>> 217 {<br>
>> 218 struct dma_fence_chain
*prev_chain = <br>
>> to_dma_fence_chain(prev);<br>
>> 219 uint64_t context;<br>
>> 220<br>
>> 221
spin_lock_init(&chain->lock);<br>
>> > 222 chain->prev = prev;<br>
>><br>
>> ---<br>
>> 0-DAY kernel test infrastructure
Open Source <br>
>> Technology Center<br>
>> <a
href="https://lists.01.org/pipermail/kbuild-all"
moz-do-not-send="true">https://lists.01.org/pipermail/kbuild-all</a>
Intel Corporation<br>
><br>
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