On 2021-07-05 11:23, Dan Carpenter wrote:
[ Ancient code, but the bug seems real enough still. -dan ]
Hello Upinder Malhi,
The patch e3cf00d0a87f: "IB/usnic: Add Cisco VIC low-level hardware
driver" from Sep 10, 2013, leads to the following static checker
warning:
drivers/iommu/iommu.c:2482 iommu_map()
warn: sleeping in atomic context
drivers/infiniband/hw/usnic/usnic_uiom.c
244 static int usnic_uiom_map_sorted_intervals(struct list_head *intervals,
245 struct usnic_uiom_reg *uiomr)
This function is always called from usnic_uiom_reg_get() which is holding
spin_lock(&pd->lock); so it can't sleep.
FWIW back in those days it wasn't really well defined whether
iommu_map() was callable from non-sleeping contexts (the arch/arm DMA
API code relied on it, for instance). It was only formalised 2 years ago
by 781ca2de89ba ("iommu: Add gfp parameter to iommu_ops::map") which
introduced the might_sleep() check that's firing there. I guess these
calls want to be updated to iommu_map_atomic() now.
Robin.
246 {
247 int i, err;
248 size_t size;
249 struct usnic_uiom_chunk *chunk;
250 struct usnic_uiom_interval_node *interval_node;
251 dma_addr_t pa;
252 dma_addr_t pa_start = 0;
253 dma_addr_t pa_end = 0;
254 long int va_start = -EINVAL;
255 struct usnic_uiom_pd *pd = uiomr->pd;
256 long int va = uiomr->va & PAGE_MASK;
257 int flags = IOMMU_READ | IOMMU_CACHE;
258
259 flags |= (uiomr->writable) ? IOMMU_WRITE : 0;
260 chunk = list_first_entry(&uiomr->chunk_list, struct usnic_uiom_chunk,
261 list);
262 list_for_each_entry(interval_node, intervals, link) {
263 iter_chunk:
264 for (i = 0; i < chunk->nents; i++, va += PAGE_SIZE) {
265 pa = sg_phys(&chunk->page_list[i]);
266 if ((va >> PAGE_SHIFT) < interval_node->start)
267 continue;
268
269 if ((va >> PAGE_SHIFT) == interval_node->start) {
270 /* First page of the interval */
271 va_start = va;
272 pa_start = pa;
273 pa_end = pa;
274 }
275
276 WARN_ON(va_start == -EINVAL);
277
278 if ((pa_end + PAGE_SIZE != pa) &&
279 (pa != pa_start)) {
280 /* PAs are not contiguous */
281 size = pa_end - pa_start + PAGE_SIZE;
282 usnic_dbg("va 0x%lx pa %pa size 0x%zx flags 0x%x",
283 va_start, &pa_start, size, flags);
284 err = iommu_map(pd->domain, va_start, pa_start,
285 size, flags);
The iommu_map() function sleeps.
286 if (err) {
287 usnic_err("Failed to map va 0x%lx pa %pa size 0x%zx with err %d\n",
288 va_start, &pa_start, size, err);
289 goto err_out;
290 }
291 va_start = va;
292 pa_start = pa;
293 pa_end = pa;
294 }
295
296 if ((va >> PAGE_SHIFT) == interval_node->last) {
297 /* Last page of the interval */
298 size = pa - pa_start + PAGE_SIZE;
299 usnic_dbg("va 0x%lx pa %pa size 0x%zx flags 0x%x\n",
300 va_start, &pa_start, size, flags);
301 err = iommu_map(pd->domain, va_start, pa_start,
302 size, flags);
iommu_map() again.
303 if (err) {
304 usnic_err("Failed to map va 0x%lx pa %pa size 0x%zx with err %d\n",
305 va_start, &pa_start, size, err);
306 goto err_out;
307 }
308 break;
309 }
310
311 if (pa != pa_start)
312 pa_end += PAGE_SIZE;
313 }
314
315 if (i == chunk->nents) {
316 /*
317 * Hit last entry of the chunk,
318 * hence advance to next chunk
319 */
320 chunk = list_first_entry(&chunk->list,
321 struct usnic_uiom_chunk,
322 list);
323 goto iter_chunk;
324 }
325 }
326
327 return 0;
328
329 err_out:
330 usnic_uiom_unmap_sorted_intervals(intervals, pd);
331 return err;
332 }
regards,
dan carpenter
_______________________________________________
iommu mailing list
iommu@xxxxxxxxxxxxxxxxxxxxxxxxxx
https://lists.linuxfoundation.org/mailman/listinfo/iommu
