From da5f7d2c8019c9dd053e2d94fdc1b3e7c03c35a5 Mon Sep 17 00:00:00 2001 From: Robin Murphy Date: Fri, 3 Dec 2021 11:44:54 +0000 Subject: [PATCH] perf/arm-cmn: Streamline node iteration Refactor the places where we scan through the set of nodes to switch from explicit array indexing to pointer-based iteration. This leads to slightly simpler object code, but also makes the source less dense and more pleasant for further development. It also unearths an almost-bug in arm_cmn_event_init() where we've been depending on the "array index" of NULL relative to cmn->dns being a sufficiently large number, yuck. Signed-off-by: Robin Murphy Link: https://lore.kernel.org/r/ee0c9eda9a643f46001ac43aadf3f0b1fd5660dd.1638530442.git.robin.murphy@arm.com Signed-off-by: Will Deacon --- drivers/perf/arm-cmn.c | 33 ++++++++++++++++++++------------- 1 file changed, 20 insertions(+), 13 deletions(-) diff --git a/drivers/perf/arm-cmn.c b/drivers/perf/arm-cmn.c index adf50d613734..da7bf779fec2 100644 --- a/drivers/perf/arm-cmn.c +++ b/drivers/perf/arm-cmn.c @@ -299,11 +299,11 @@ static struct arm_cmn_node *arm_cmn_node_to_xp(struct arm_cmn_node *dn) static struct arm_cmn_node *arm_cmn_node(const struct arm_cmn *cmn, enum cmn_node_type type) { - int i; + struct arm_cmn_node *dn; - for (i = 0; i < cmn->num_dns; i++) - if (cmn->dns[i].type == type) - return &cmn->dns[i]; + for (dn = cmn->dns; dn->type; dn++) + if (dn->type == type) + return dn; return NULL; } @@ -941,8 +941,8 @@ static int arm_cmn_event_init(struct perf_event *event) { struct arm_cmn *cmn = to_cmn(event->pmu); struct arm_cmn_hw_event *hw = to_cmn_hw(event); + struct arm_cmn_node *dn; enum cmn_node_type type; - unsigned int i; bool bynodeid; u16 nodeid, eventid; @@ -974,10 +974,12 @@ static int arm_cmn_event_init(struct perf_event *event) nodeid = CMN_EVENT_NODEID(event); hw->dn = arm_cmn_node(cmn, type); - for (i = hw->dn - cmn->dns; i < cmn->num_dns && cmn->dns[i].type == type; i++) { + if (!hw->dn) + return -EINVAL; + for (dn = hw->dn; dn->type == type; dn++) { if (!bynodeid) { hw->num_dns++; - } else if (cmn->dns[i].id != nodeid) { + } else if (dn->id != nodeid) { hw->dn++; } else { hw->num_dns = 1; @@ -1332,7 +1334,7 @@ static int arm_cmn_init_dtcs(struct arm_cmn *cmn) cmn->xps = arm_cmn_node(cmn, CMN_TYPE_XP); - for (dn = cmn->dns; dn < cmn->dns + cmn->num_dns; dn++) { + for (dn = cmn->dns; dn->type; dn++) { if (dn->type != CMN_TYPE_XP) arm_cmn_init_node_to_xp(cmn, dn); else if (cmn->num_dtcs == 1) @@ -1382,6 +1384,7 @@ static int arm_cmn_discover(struct arm_cmn *cmn, unsigned int rgn_offset) u32 xp_offset[CMN_MAX_XPS]; u64 reg; int i, j; + size_t sz; cfg_region = cmn->base + rgn_offset; reg = readl_relaxed(cfg_region + CMN_CFGM_PERIPH_ID_2); @@ -1408,14 +1411,13 @@ static int arm_cmn_discover(struct arm_cmn *cmn, unsigned int rgn_offset) cmn->num_dns += FIELD_GET(CMN_CI_CHILD_COUNT, reg); } - /* Cheeky +1 to help terminate pointer-based iteration */ - cmn->dns = devm_kcalloc(cmn->dev, cmn->num_dns + 1, - sizeof(*cmn->dns), GFP_KERNEL); - if (!cmn->dns) + /* Cheeky +1 to help terminate pointer-based iteration later */ + dn = devm_kcalloc(cmn->dev, cmn->num_dns + 1, sizeof(*dn), GFP_KERNEL); + if (!dn) return -ENOMEM; /* Pass 2: now we can actually populate the nodes */ - dn = cmn->dns; + cmn->dns = dn; for (i = 0; i < cmn->num_xps; i++) { void __iomem *xp_region = cmn->base + xp_offset[i]; struct arm_cmn_node *xp = dn++; @@ -1484,6 +1486,11 @@ static int arm_cmn_discover(struct arm_cmn *cmn, unsigned int rgn_offset) /* Correct for any nodes we skipped */ cmn->num_dns = dn - cmn->dns; + sz = (void *)(dn + 1) - (void *)cmn->dns; + dn = devm_krealloc(cmn->dev, cmn->dns, sz, GFP_KERNEL); + if (dn) + cmn->dns = dn; + /* * If mesh_x wasn't set during discovery then we never saw * an XP at (0,1), thus we must have an Nx1 configuration. -- 2.11.0