kernel.git/net/core/net-sysfs.c, branch linux-5.13.y

net-sysfs: remove possible sleep from an RCU read-side critical section

2021-03-22T20:28:13Z

xps_queue_show is mostly made of an RCU read-side critical section and calls bitmap_zalloc with GFP_KERNEL in the middle of it. That is not allowed as this call may sleep and such behaviours aren't allowed in RCU read-side critical sections. Fix this by using GFP_NOWAIT instead. Fixes: 5478fcd0f483 ("net: embed nr_ids in the xps maps") Reported-by: kernel test robot Suggested-by: Matthew Wilcox Signed-off-by: Antoine Tenart Signed-off-by: David S. Miller

net-sysfs: move the xps cpus/rxqs retrieval in a common function

2021-03-18T21:56:22Z

Most of the xps_cpus_show and xps_rxqs_show functions share the same logic. Having it in two different functions does not help maintenance. This patch moves their common logic into a new function, xps_queue_show, to improve this. Signed-off-by: Antoine Tenart Signed-off-by: David S. Miller

net-sysfs: move the rtnl unlock up in the xps show helpers

2021-03-18T21:56:22Z

Now that nr_ids and num_tc are stored in the xps dev_maps, which are RCU protected, we do not have the need to protect the maps in the rtnl lock. Move the rtnl unlock up so we reduce the rtnl locking section. We also increase the reference count on the subordinate device if any, as we don't want this device to be freed while we use it (now that the rtnl lock isn't protecting it in the whole function). Signed-off-by: Antoine Tenart Signed-off-by: David S. Miller

net: move the xps maps to an array

2021-03-18T21:56:22Z

Move the xps maps (xps_cpus_map and xps_rxqs_map) to an array in net_device. That will simplify a lot the code removing the need for lots of if/else conditionals as the correct map will be available using its offset in the array. This should not modify the xps maps behaviour in any way. Suggested-by: Alexander Duyck Signed-off-by: Antoine Tenart Signed-off-by: David S. Miller

net: remove the xps possible_mask

2021-03-18T21:56:22Z

Remove the xps possible_mask. It was an optimization but we can just loop from 0 to nr_ids now that it is embedded in the xps dev_maps. That simplifies the code a bit. Suggested-by: Alexander Duyck Signed-off-by: Antoine Tenart Signed-off-by: David S. Miller

net: embed nr_ids in the xps maps

2021-03-18T21:56:22Z

Embed nr_ids (the number of cpu for the xps cpus map, and the number of rxqs for the xps cpus map) in dev_maps. That will help not accessing out of bound memory if those values change after dev_maps was allocated. Suggested-by: Alexander Duyck Signed-off-by: Antoine Tenart Signed-off-by: David S. Miller

net: embed num_tc in the xps maps

2021-03-18T21:56:22Z

The xps cpus/rxqs map is accessed using dev->num_tc, which is used when allocating the map. But later updates of dev->num_tc can lead to having a mismatch between the maps and how they're accessed. In such cases the map values do not make any sense and out of bound accesses can occur (that can be easily seen using KASAN). This patch aims at fixing this by embedding num_tc into the maps, using the value at the time the map is created. This brings two improvements: - The maps can be accessed using the embedded num_tc, so we know for sure we won't have out of bound accesses. - Checks can be made before accessing the maps so we know the values retrieved will make sense. We also update __netif_set_xps_queue to conditionally copy old maps from dev_maps in the new one only if the number of traffic classes from both maps match. Signed-off-by: Antoine Tenart Signed-off-by: David S. Miller

net-sysfs: make xps_cpus_show and xps_rxqs_show consistent

2021-03-18T21:56:22Z

Make the implementations of xps_cpus_show and xps_rxqs_show to converge, as the two share the same logic but diverted over time. This should not modify their behaviour but will help future changes and improve maintenance. Signed-off-by: Antoine Tenart Signed-off-by: David S. Miller

net-sysfs: store the return of get_netdev_queue_index in an unsigned int

2021-03-18T21:56:22Z

In net-sysfs, get_netdev_queue_index returns an unsigned int. Some of its callers use an unsigned long to store the returned value. Update the code to be consistent, this should only be cosmetic. Signed-off-by: Antoine Tenart Signed-off-by: David S. Miller

net-sysfs: convert xps_cpus_show to bitmap_zalloc

2021-03-18T21:56:22Z

Use bitmap_zalloc instead of zalloc_cpumask_var in xps_cpus_show to align with xps_rxqs_show. This will improve maintenance and allow us to factorize the two functions. The function should behave the same. Signed-off-by: Antoine Tenart Signed-off-by: David S. Miller